SCIENCE SCIENCE FOR FOR SOUTH SOUTH AFRICA AFRICA
ISSN 1729-830X ISSN 1729-830X
VOLUME 7 • NUMBER 1 • 2011 VOLUME 3 • NUMBER 2 • 2007 R29.95 R20
Chemistry: ‘queen of sciences’
& Marie Curie a star
The Periodic Table:
fundamental to chemistry
SASOL’s Fischer Tropsch process: fuel innovation
South Africa’s chemical industry:
a long history
Ecological networks: protecting biodiversity Scorched, frozen or flooded: climate change and weather Hoodia research: biotechnology to the fore
A C AACDAEDMEYM YO FO FS C I EI ENNCCEE OOFF SS O U TT HH AAFFRRI C I CA A SC OU
The ‘queen of sciences’ QUEST looks at Marie Curie’s contribution to chemistry in particular and science in general. 8
The Periodic Table of the elements Without understanding the Periodic Table, chemistry can remain a mystery. QUEST explains.
The Fischer-Tropsch Process: generating synthetic fuels Cathrin Welker-Nieuwoudt SASOL has a history of innovation in the field of synthetic fuels.
Chemistry in South Africa – a long-established industry Mike Booth
Contents VOLUME 7 • NUMBER 1 • 2011
Mining and stock diseases were major forces in the development of the local chemical industry. 24
From plant to production: the Hoodia story Vinesh Maharaj
Indigenous knowledge and biotechnology team up. 30
Cameras and sound: new approached in the study of estuarine fish New technology aids in the understanding of aquatic biodiversity.
Ecological networks: the key to biodiversity conservation
Ten years of the InfraRed Survey Facility
Lize Joubert and Michael Samways
Ian Glass and Phil Charles
Industry can be part of biodiversity conservation.
An update of this important astronomical facility in South Africa.
Scorched, frozen or flooded! What’s happening to the weather?
Elephants and waves Jan Smit
Seeing physics in everyday life.
Are extreme events a sign of climate change?
Green chemistry: from the chemical industry to everyday life
Fact file Radioactivity – p. 6 • Analytical techniques – p. 29
Lilian Mammimo Chemistry is no longer a ‘dirty industry’.
The International Year of Chemistry Global Experiment
Diary of Events
Back page science • Mathematical puzzle
Rovani Sigamoney UNESCO and IUPAC launch the IYC in Cape Town in March 2011. 21
Natural products in South Africa: a brief history Siegfried Drewes The history of natural product production in South Africa started a long time ago.
Quest 7(1) 2011 1
SCIENCE SCIENCE FOR FOR SOUTH SOUTH AFRICA AFRICA
ISSN 1729-830X ISSN 1729-830X
VOLUME 7 • NUMBER 1 • 2011 VOLUME 3 • NUMBER 2 • 2007 R29.95 R20
Chemistry: ‘queen of sciences’
& Marie Curie a star
The Periodic Table:
fundamental to chemistry
SASOL’s Fischer Tropsch process: fuel innovation
South Africa’s chemical industry:
a long history
Ecological networks: protecting biodiversity Scorched, frozen or flooded: climate change and weather Hoodia research: biotechnology to the fore
A C AACDAEDMEYM YO FO FS C I EI ENNCCEE OOFF SS O U TT HH AAFFRRI C I CA A SC OU
Images: CSIR, SASOL, Wikimedia commons
SCIENCE FOR SOUTH AFRICA
Editor Dr Bridget Farham Editorial Board Roseanne Diab (University of KwaZulu-Natal) (Chair) Michael Cherry (South African Journal of Science) Phil Charles (SAAO) Anusuya Chinsamy-Turan (University of Cape Town) George Ellis (University of Cape Town) Peter Vale (University of Johannesburg) Penny Vinjevold (Western Cape Department of Education) Correspondence and The Editor enquiries PO Box 663, Noordhoek 7979 Tel.: (021) 789 2331 Fax: (021) 789 2233 e-mail: firstname.lastname@example.org (For more information visit www.questinteractive.co.za) Advertising enquiries Barbara Spence Avenue Advertising PO Box 71308 Bryanston 2021 Tel.: (011) 463 7940 Fax: (011) 463 7939 Cell: 082 881 3454 e-mail: email@example.com Subscription enquiries Patrick Nemushungwa and back issues Tel.: (012) 349 6624 e-mail: Patrick@assaf.org.za Copyright © 2011 Academy of Science of South Africa
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The 'queen of sciences' T he introductory article in this edition of QUEST, with a focus on the International Year of Chemistry, essentially celebrates the life of one woman in science, Marie Curie. Obviously, as a woman and a scientist, I have a particular interest in the role of women in science and my background is probably the reason I chose the sciences. My grandmother was born in 1899 into an unassuming middle-class family in Edinburgh, Scotland. She had three sisters and a brother who died when he was a child. Her mother was the breadwinner. But she was an ambitious young woman who excelled at school and won a scholarship to Edinburgh University, where she studied chemistry, mathematics and ‘natural philosophy’ – an old term that was used for the study of nature and the physical universe that was used before the development of modern science. There was only one other woman in her class, which was made up largely of men who were returning to university after the First World War (1914-1918). Three years before my grandmother was born JJ Thomson discovered the electron, finally showing that the atom was not the smallest indivisible unit of matter. Not all that long before this, in 1869, Mendeleev had published his first version of the Periodic Table. All this is to put into context my grandmother’s experience as young woman studying chemistry in the early part of the 1900s. By the time she started to study chemistry, we knew that the atom contained electrons and a nucleus and Niels Bohr had just (in 1913) described the orbital theory of electrons around the nucleus of the atom. At the time that Bohr was working, another woman chemist, Margaret Todd, coined the term isotope and of course the Curies were busy with their now famous and pivotal work on radioactive decay. However, as an undergraduate university student of chemistry, my grandmother’s experience would have been rather more ordinary. She would have learnt the Periodic Table, she would have had a basic understanding of isotopes and radioactive decay and she would have learnt qualitative and quantitative analytical techniques. But what a time to be studying chemistry – these were the decades of Einstein, Bohr, Planck, Rutherford, the Curies – the list of names of famous chemists and physicists is almost endless. It was a time of enormous discovery and innovation. By the time my grandmother was teaching senior school chemistry in Johannesburg during the Second World War (1939-1945) and beyond we had literally taken a quantum leap in our understanding of the physical world around us. She must have spent her entire teaching career learning new material. My grandmother died at the age of 91. In her lifetime she saw huge changes in the sciences, all based on the early work done by the pioneers who were working when she was first studying. Our understanding of chemistry and the physical world around us – natural philosophy to use the old term – is at a level where we are starting to understand the chemistry, physics and mathematics of sub-atomic particles, leading to major advances in other branches of science, and through technology, to breakthroughs in the way in which science contributes to everyday life. This is the joy of science – and chemistry is fundamental to the use of science in our daily lives. Enjoy the subject! Find more good science on www.questinteractive.co.za.
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2 Quest 7(1) 2011
Bridget Farham Editor – QUEST: Science for South Africa All material is strictly copyright and all rights are reserved. Reproduction without permission is forbidden. Every care is taken in compiling the contents of this publication, but we assume no responsibility for effects arising therefrom. The views expressed in this magazine are not necessarily those of the publisher.
The ‘queen of sciences’ While chemistry has been described as ‘the queen of sciences’, one of its most famous researchers was a woman. QUEST looks at Marie Curie’s contribution to the science of chemistry.
hemistry is really the queen of the sciences. If there is any one subject that an educated person should know in the world, it is chemistry.’ Rogern Kornberg, Nobel Laureate in Chemistry 2006.
The birthplace of Marie Skłodowska-Curie in Warsaw, Poland. Image: Wikimedia commons
Image: Wikimedia commons
Marie Curie’s Nobel Prize for Chemistry.
Image: Wikimedia commons
of the nature and compounds of this remarkable element’. Marie Curie now had the status of scientists such as Albert Einstein and many others who transformed the sciences of physics and chemistry at the beginning of the 20th century. ▲ ▲
Marie Curie – an inspiration to women in science 2011 is the International Year of Chemistry. This year was designated as such partly because the year 2011 coincides with the 100th anniversary of the Nobel Prize in Chemistry that was awarded to Madame Marie Curie – and so is also an opportunity to celebrate the contributions of women to science. Marie Curie is a legendary figure in science. She received the highest recognition for her work twice – she was awarded the Nobel Prize in 1903 and again in 1911. The first time she shared the third-ever Nobel Prize in Physics with Henri Becquerel and Pierre Curie. Half of the prize went to Henri Becquerel for ‘the discovery of spontaneous radioactivity’ and half to Pierre and Marie Curie for ‘their joint researchers on the radiation phenomena discovered by Henri Becquerel’. At this time the use of the word ‘radioactivity’ was particularly interesting because it was associated with Henri Becquerel, when in fact, the word was first used by Marie Curie in her doctorate, which was presented at the Sorbonne, Paris, in 1903. She and her husband, Pierre, had already announced the discovery of the elements radium and polonium. However, at this time, physicists and chemists were still disputing the existence of ‘radioactivity’ and the chemists on the Nobel Prize jury would not mention the word ‘radium’ in the heading of a Nobel Prize for Physics. In 1911 Marie Curie was awarded the Nobel Prize in Chemistry for ‘her services to the advancement of chemistry by the discovery of the elements polonium and radium, by the isolation of radium, and the study
Quest 7(1) 2011 3
Who was Marie Curie? Marie Curie was born Marie Skłodowska in Warsaw, Poland on 7 November 1867. In 1891 she left Poland for Paris, where she registered at the Sorbonne to study science – physics, mathematics and chemistry. She was a woman scientist in a male-dominated society. In 1893 she obtained a degree in physics and started working in industry, but carried on studying at the Sorbonne, and in 1894 she was awarded a degree in mathematics. In 1895 she married Pierre Curie, another physicist, and began a marriage that was also a scientific collaboration. A century ago it would have been exceptionally difficult for a woman to be recognised by the academic community, and indeed the public, without the support of a father, a husband or a brother. Marie Curie’s research At the age of 24 Marie registered for a master’s degree in physics at the
Sorbonne. She graduated in 1893 with the highest score in the masters examination. However, her studies did not come easily to her because she found that she was not as well prepared by her previous studies in Poland as she thought she would be. As a result, she worked ‘a thousand times as hard as at the beginning of my stay [in Paris]’. After her master’s degree she was given a small grant to study the magnetic properties of different kinds of tempered steels. She continued this research after her marriage to Pierre Curie and, a few weeks after her first daughter was born, she decided to prepare a thesis on the new radiation discovered by Henri Becquerel. This was in 1897. In June 1903 she defended her thesis ‘Researches on radioactive substances’. This was also the year that she and Pierre shared the Nobel Prize in Physics with Henri Becquerel.
After winning the Nobel Prize, Pierre Curie was appointed a full professor at the Sorbonne and Marrie was appointed as his assistant. By the begininning of 1906 Marie’s life was divided between experiments about one or other question raised in the rapidly developing field of radioactivity and spending time with her family. However, Marie’s marriage was tragically cut short when Pierre was killed in an accident with a horsedrawn carriage in 1906. Ironically, his death lead to something of a milestone in women’s rights – or those of women scientists – when she was put in charge of Pierre’s lectures and his laboratory. This opened the door for other women to attain high level academic positions. After Pierre’s death the council of the Faculty of Science at the Sorbonne, at the insistence of fellow professors, finally decided to give Marie his chair as well as the
The history of polonium and radium In 1896 Henrie Becquerel discovered uranic rays. These were rays given off by compounds and minerals of uranium that could blacken a photographic plate over several months. The ability of these compounds to blacken these plates did not seem to get less over time, which appeared to violate the principle that energy can be transformed, but can never be created or destroyed. So what was the source of this energy? With Pierre Curie’s encouragement, Marie Curie started to investigate this phenomenon for her doctoral research. Within eight months of starting this research Marie had found two elements, polonium and radium and founded a new scientific field, radioactivity. The uranic rays found by Becquerel not only blackened a photographic plate, they also made air conduct electricity – something that could be measured. In 1880, Pierre Curie and his brother Jacques had discovered piezoelectricity – which is the production of electric charges when pressure is applied to hemihedral crystals such as quartz. A hemihedral crystal is one that has only half the number of faces needed for complete symmetry. Pierre Curie invented a device that could quantify the emission of uranic rays. At the same time Marie was looking at substances other than uranium to see if there were any that could also make air conduct electricity. She tested a large number of rocks and minerals, using the activity of metallic uranium as a reference. She found that all compounds and minerals that contained uranium were active. There were two that were more active than metallic uranium itself – pitchblende (uraninite) and chalcolite (a natural uranium phosphate) – both minerals of uranium. Marie noted that her findings suggested that an unknown element was present in the uraniferous minerals that were more active than uranium. At this stage the hunt for the missing element became extremely urgent and Pierre Curie abandoned his own research to join his wife in the search.
The ore pitchblende, now called uraninite.
Image: Wikimedia commons
The discovery of polonium – 18 July 1898 The research on uranic rays now turned from physics to chemistry. It became necessary to separate and identify a substance whose
4 Quest 7(1) 2011
An example of chalcolite.
Image: Wikimedia commons
Pierre and Marie Curie working together in their laboratory. Image: Wikimedia commons
The first Solvay Conference in 1911 at the Hotel Metropole, Brussels. Seated (L-R): W. Nernst, M. Brillouin, E. Solvay, H. Lorentz, E. Warburg, J. Perrin, W. Wien, M. Curie, and H. Poincaré. Standing (L-R): R. Goldschmidt, M. Planck, H. Rubens, A. Sommerfeld, F. Lindemann, M. de Broglie, M. Knudsen, F. Hasenöhrl, G. Hostelet, E. Herzen, J.H. Jeans, E. Rutherford, H. Kamerlingh Onnes, A. Einstein and P. Langevin. Image: Wikimedia commons
directorship of the laboratory. Two years later she was appointed as a full professor. She continued her work at the laboratory, focusing on radiochemical research, calibration of radium sources and the preparation of
the first radium standard. Marie was awarded the Nobel Prize in Chemistry in 1911 for the discovery of polonium and radium. Marie Curie was a pioneer in science and a pioneer for the rights of women
chemical properties were not known. The hypothetical element could also be followed by tracing its radioactivity. This led Pierre and Marie Curie to a new process in chemical research. They separated using the normal procedures of analytical chemistry and also measured the radioactivity of all compounds that they separted in this way. Because neither Pierre nor Marie Curie were chemists they were assisted by a chemist, Gustave Bémont. The first research was done on pitchblende, which was two and a half times more active than uranium. The research started in April and on the 27 June Marie Curie precipitated a solution that contained the active substance. This solid that she precipitated out was 300 times more active than uranium. On 18 July, Pierre Curie obtained a deposit 400 times more active than uranium. On 18 July 1898, Pierre and Marie Curie wrote ‘We believe that the substance we recovered from pitchblende contains a heretofore unkown element, similar to bismuth in its analytical properties. If the existence of this new metal is confirmed, we propose that it be named polonium in honour of the native land of one of us’. The new element was give the symbol Po. The discovery of this element gave us the word ‘radioactive’ for the first time. The announcement of a new element that remained invisible and was identified entirely on the basis of its emission of ‘uranic rays’ was unique in the history of chemistry. However, no such claim could be considered valid until a pure substance had been isolated, the atomic weight of the element had been determined and its spectral lines had been measured. The spectral lines of an element are measured using spectroscopy. Atoms and elements have unique spectra. These spectra can be interpreted to derive information about the atoms and molecules, and they can also be used to detect, identify and quantify chemicals. When the new element was examined for spectral lines, no new lines could be found, which dismayed the Curies, who wrote, ‘This fact does not favour the idea of the exitence of a new metal’. The Curies had managed to isolate polonium from uranium, but they did not understand the relationship between the two elements. They thought that the entire material was a mixture
in science and in general. Her presence at the first Solvay Conference in 1911 was remarkable. These conferences are convened to discuss the most important ideas in physics and chemistry that are current. The subject of the first conference was radiation and the quanta. The photograph on the left shows Marie Curie among the greats of science in her day. Names such as Einstein and Rutherford should be familiar to you! ■ This article was put together using the current issue of Chemistry International, Vol. 33 (1): JanuaryFebruary 2011.
and they knew nothing about radioactive decay. The half life of polonium is 138 days, so their discovery was very much a matter of chance since their experiments were peformed within three months. A few years later, the Curies were astonished to notice that the polonium was progressively disappearing. They carried on trying to work out whether or not polonium really was a new metal. Eventually, in 1910 Marie Curie and a co-worker separated a final product that weighed 2 mg and contained about 0.1 mg of polonium from several tons of residues of uranium ores. The spark spectrum of this sample showed for the first time a few lines characteristic of the element. The new element could be placed to the right of bismuth in the periodic table and had an atomic number of 84. Polonium was Marie Curie’s element – the subsequent discoveries of the atomic nucleus, artificial radioactivity and fission were all performed with her polonium.
The discovery of radium – 26 December 1898 The Curies suspected that there was another radioactive element in the pitchblende which behaved like ‘nearly pure barium’. Their hypothesis was confirmed in three steps. First, they confirmed that ‘normal’ barium was inactive. Second, they found that a radioactive substance coud be concentrated from barium chloride contained in pitchblende. They carried out this concentration process until the activity of this radioactive substance was 900 times greater than that of uranium. The third argument was the deciding one – the spectrum of radioactive barium chloride contained several lines that could not be assigned to any known element and whose intensity was increased with the radioactivity. The Curies concluded, ‘We think this is a very serious reason to believe that the new radioactive substance contains a new element to which we propose to give the name radium’. Marie Curie became obsessed with working out the atomic mass of radium, which she determined to be 225±1. We now know that the atomic mass of radium is 226.0254. Radium has a half life of 16 000 years, its concentration in ores is about 5 000 times greater than that of polonium and it could readily be assigned its place in the periodic table.
Quest 7(1) 2011 5
Radioactivity A This diagram shows the process of radioactive decay in a general way.
Alpha decay is an example of radioactive decay in which an atomic nucleus emits an alpha particle and so transforms â€“ or decays â€“ into an atom with a mass number 4 less and an atomic number 2 less. Image: Wikimedia commons
radioactive element or substance is one that shows radioactive decay. Radioactive decay is the process in which the atomic nucleus of an unstable atom loses energy by emitting (giving off) ionising particles. This is called ionising radiation. This emission is spontaneous, which means that the emission does not depend on or need interaction with another particle from outside the atom. There are many different types of radioactive decay. One example is alpha decay. The decay, or loss of energy, results when an atom with one type of nucleus, called the parent radionuclide, transforms to an atom with a nucleus in a different state or a different nucleus, called the daughter nuclide. Often the parent and the daughter are different chemical elements. For example, carbon-14 (the parent) emits radiation (a beta particle, antineutrino and a gamma ray) and transforms to a nitrogen-14 atom (the daughter). There is also radioactive decay that does not result in transumutation but only in a decrease in energy in the nucleus. This results in the same element as before, but with a nucleus in a lower energy state. The SI unit of activity is the becquerel (Bq) and one Bq is defined as one transformation (or decay) per second.
The discovery of radioactivity Radioactivity was first discovered in 1896 by the French physicist Henri Becquerel. He was working on phosphorescent materials. These materials glow in the dark after they have been exposed to light. He thought that the glow produced in cathode ray tubes by X-rays might be connected with phosphorescence. To examine this he wrapped a photographic plate in black paper and placed different phosphorescent salts on it. All the results were negative until
Alpha particles can be completely stopped by a sheet of paper, beta particles can be stopped by aluminium shielding. Gamma rays can only be stopped by much more substantial barriers, such as a very thick layer of lead.
6 Quest 7(1) 2011
The trefoil symbol is used to show radioactive material.
he used uranium salts. The uranium salts produced a deep blackening of the plates. These radiations were called Becquerel rays. However, the plate blackened when the mineral was in the dark, so this had nothing to do with phosphoresence. Non-phosphorescent salts of uranium and metallic uranium also blackened the plate, which meant that there was a form of radiation that could pass through paper that was making the plate black. Early researchers such as Pierre and Marie Curie, Edward Rutherford and Becquerel himself, eventually found that many other chemical elements besides uranium have radioactive isotopes.
Types of decay The early researchers also found that an electrical or magnetic field could split radioactive emissions into three types of beams. The rays were given the alphabetic names alpha, beta and gamma. Alpha rays carry a positive charge, beta rays carry a negative charge and gamma rays are neutral. We now know that there are other types of decay, but alpha, beta and gamma decay are the most common.
The dangers of radioactive substances The early researchers into radioactivity did not realise that radioactivity and radiation were dangerous. The immediate effects of radiation were first seen by the electrical engineer and physicist Nikola Tesia when he intentionally exposed his fingers to X-rays in 1896. He published his observations on the burns that he suffered (and later recovered from), but thought they were caused by ozone and not by the X-ray radiation. The genetic effects of radiation, including the way in which it can increase the risk of cancer, were recognised much later. In 1927 Hermann Muller published research about genetic effects and was awarded the Nobel Prize in 1946 for his findings. In fact, before the biological effects of radiation were known, many doctors and corporations were marketing radioactive substances as patent medicines. Examples were radium enema treatments and waters containing radium to be drunk as tonics! Marie Curie spoke out against this type of treatment, saying that we did not yet know enough about the effects of radiation on the human body. She later died of aplastic anaemia, probably as a result of exposure to ionising radiation. By the 1930s after a number of cases of bone necrosis and death in enthusiasts, radium-containing medical products had nearly vanished from the market.
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The periodic table of the elements Chemistry is fundametal to the world around us, but sometimes difficult to understand. But, if you understand the periodic table of the elements, you will find the subject makes far more sense. QUEST explains.
he modern periodic table of the elements is a table in which the known chemical elements are arranged in order of their atomic numbers. The really important feature of the periodic table is that
the position of each element in the table indicates both its physical and chemical properties. If you understand this, and know how these physical and chemical properties change as you move through the periodic table, you will have a good understanding of the basics of chemistry. Element â€“ a pure chemical substance that is made up of one type of atom. All chemical matter consists of elements. Examples are carbon, iron, copper, silver and gold. For more information on the atom see QUEST 6(3), page 13. Each element has a specific atomic number. This is the number of protons in its nucleus. Proton â€“ a sub-atomic particle that carries an electrical charge of + 1. Protons can also exist on their own. The hydrogen ion (H+) is a proton. Netron â€“ an electrically neutral particle in the nucleus of the atom.
A portrait of Dimitri Mendeleev.
Image: Wikimedia Commons
Dimitri Mendeleev The periodic table as we know it now was first published by the Russian inventor and chemist, Dimitri Mendeleev in 1869. This version still forms the basis of the modern periodic table. Mendeleev was able to use the physical and chemical properties of the known groups of elements to predict the properties of elements that had not been discovered
in the time that he was working. Mendeleev was a teacher and he wrote a two-volume textbook of chemistry, Principles of Chemistry that was thought of as the major chemistry textbook of the time. He started by classifying elements according to their chemical properties and while he was doing this he noticed patterns that led him to suggest his periodic table. Understanding the periodic table You know that the periodic table shows the arrangement of the elements in order of their atomic number. The atomic number is the number of protons in the nucleus of an atom. The atomic number determines what the element is, for example any atom with six protons is carbon. Each atom also has a mass number, which is the total number of protons and neutrons in one atom of an element. A neutron is a sub-atomic particle in the nucleus of an atom. The periodic table shown here shows the atomic number of each element above the symbol for the element. The periodic table is divided into groups, which are the columns in the table, and periods, which are the rows in the table. The elements are arranged so that period one starts Isotopes
The periodic table of the elements.
8 Quest 7(1) 2011
An isotope is an atom of an element in which the number of neutrons is different from that in another atom of the same element. Isotopes of an element have the same atomic number, but different mass numbers. Isotopes are distinguished from each other by writing the mass number by the name or symbol of the element. For example, carbon-12, carbon-13 and carbon-14. These are all isotopes of carbon. Recent research in chemistry suggests that what we know as the periodic table of the elements is in fact a subset of the periodic table of the isotopes. So, like most things in science, the periodic table is not cast in stone. It will be constantly reviewed and future periodic tables may not be the same as the one being taught today.
This diagram shows an atom with its electron shells. The element in this diagram is sodium, which has an atomic number of 11, with 11 electrons. Left: A sculpture of the periodic table in circular layout with a portrait of Dimitri Mendeleev in the middle. Image: Wikimedia Commons
with hydrogen and moves from left to right across each period in order of increasing atomic number. Periods
Periods are the horizontal rows of elements in the periodic table. There are seven periods. Period 1 has only two elements, hydrogen (H) and helium (He). Periods 2 and 3 each contain eight elements and are called the short periods. Periods 4, 5, 6, and 7 each contain between 18 and 32 elements. They are called long periods. As you move from left to right across a period, the atomic number increases by one from one element to the next. Each successive element has one more electron it the outer shell of its atoms. All elements in the same periods have the same number of shells. The regular change in the number of electrons from one element to the next is what leads to the regular pattern of change in the chemical properties of the elements across a period. For example, if you look at period 3 you will see the following sequence (see table). In principle, if you understand the relationship between atomic weight and the electron configuration of the elements you will be able to predict their chemical and physical properties. However, it is important to remember that this theory breaks down for heavier elements, although this simple approach will definitely help you to understand the basics of chemistry. Groups
A group is a vertical column of elements in the periodic table. All
groups are numbered and some have names, for example the transition metals. Elements in the same group have the same number of electrons in their outer shell and so have similar chemical properties.
Transition metals The transition metals are an interesting group of metals that have some properties in common. They are hard, tough, shiny, malleable and ductile. They conduct heat and electricity and have high melting points, high boiling points and are dense metals. Examples are iron, nickel, manganese, titanium and zinc.
Metals and non-metals
The properties of metals versus nonmetals are a good way to understand what we mean by the properties of an element in general. A metal is an element that has particular physical properties that distinguish it from a non-metal. Elements on the left of a period have metallic properties. As you move to the right the elements gradually become less metallic. Elements that are not distinctly metal or non-metal, but have a mixture of properties are called metalloids. Elements that lie to the right of metalloids in a period are non-metals. Element Atomic number
Sodium (Na) 11
Metallic Metal character
Conductivity is the ability of a substance to allow the flow of a current. Malleability is the ability of a substance to be moulded into different shapes, including being hammered into thin sheets, for example aluminium sheeting. Ductility is the ability of a substance to be stretched, for example copper can be stretched into thin wires. â– A good online reference (that has won several awards) for the periodic table is http://www.webelements.com/.
Magnesium Aluminium Silicon (Mg) (Al) (Si)
Phosphorus Sulphur (P) (S)
Semi-metal Non-metal Non-metal Non-metal Non-metal (metalloid)
Metals versus non-metals Property
Solid (except mercury)
Solid, liquid or gas (bromine is the only liquid)
Mainly non-shiny (iodine is one of the exceptions)
Poor (except graphite)
Generally low (except carbon)
Quest 7(1) 2011 9
The Fischer-Tropsch Process: generating synthetic fuels SASOL was a pioneer in the use of the Fischer-Tropsch process to provide South Africa with fuel. Cathrin Welker-Nieuwoudt and her colleagues explain.
A familiar site around the country – a SASOL garage.
liquid hydrocarbons. F-T synthesis has been one of SASOL’s core technologies since the 1950s. The F-T process involves a series of chemical reactions that lead to the production of many different hydrocarbons. For example, the reaction below provides alkanes: (2n+1) H2 + n CO CnH(2n+2) + n H2O The process has its origin in the first hydrocarbon synthesis reaction, which is the reaction of synthesis gas over nickel and cobalt catalysts to form the gas methane, which was first reported in 1902. In the following years, various groups worked on this promising reaction. The next major breakthrough in this field was the synthesis of higher hydrocarbons under atmospheric pressure on cobalt, nickel and iron catalysts by Franz Fischer and Hans Tropsch in 1925 – hence
Alkanes are substances also known as paraffins or saturated hydrocarbons. They are chemical compounds that consist only of the elements carbon (C) and hydrogen (H). The most important source of alkanes are natural gas and crude oil.
The gas methane is the simplest alkane – this is its chemical structure. Image: SASOL
Fischer-Tropsch synthesis – when, how and why It is widely accepted that crude oil has a limited future of approximately 30 years at commonly projected energy and fuel needs. On the other hand, we have hundreds of years of coal, tar sands, natural gas as well as biomass reserves available around the globe. All these hydrocarbon sources can be used for the generation of synthesis gas (syngas), which is a mixture of hydrogen and carbon monoxide, which is the gas mixture (feedstock) that is used for Fischer-Tropsch (FT) synthesis (see Figure 1). The F-T process is at the heart of gas/coal/ biomass to liquids technology, that produces a petroleum substitute, for use as synthetic fuel and chemicals. The F-T process is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into
Catalysts used in the F-T process A catalyst is a substance that accelerates the rate of a chemical reaction without being used up in the reaction itself. A catalyst basically provides lower energy pathways for the breaking and formation of chemical bonds in molecules. Catalysts may take part in multiple chemical reactions. Catalysts do not last forever and generally lose their activity with time. Substances that reduce the action of catalysts are called catalyst inhibitors if reversible, and catalyst poisons if irreversible. Promoters are substances that increase the catalytic activity, even though they are not catalysts by themselves. A number of different catalysts can be used for the F-T process, but the most common are the transition metals cobalt, iron and ruthenium. Nickel can be used but tends to favour methane formation. Cobalt catalysts are preferred for the F-T process when the feedstock is natural gas. Iron catalysts are preferred for lower quality feedstocks such as coal or biomass. Cobalt catalysts have longer lifetimes than their iron counterparts.
Figure 1: Different stages of the coal/gas and biomass to liquid synthesis. Image: SASOL
Quest 7(1) 2011 11
Figure 2. Fischer-Tropsch synthesis reactors that are currently in use. Image: SASOL
Table 1. A historical perspective of the Fischer-Tropsch process First generation (1920s to early 1970s) ■ Strategic considerations ■ Mainly fuel value ■ Limited chemical value Second generation (1970s to late 1980s) ■ Economic considerations ■ Reactor technology development (SAS, Slurry bed) ■ Chemical value significant ■ Expensive and complex separation processes Third generation (2000–current) ■ Greater product flexibility between fuels/chemicals ■ Direct production of high-value chemicals ■ Minimise separation costs ■ More effective catalyst/reactor systems
the name Fischer-Tropsch process. Both men worked at the KaiserWilhelm Institute für Kohleforschung in Mühlheim, Germany. By 1938 nine Fischer-Tropsch plants were operating in Germany with a capacity of 600 000 tons per annum. In the 1940s and 1950s the US Bureau of Mines revived interest in F-T technology by replacing the expensive cobalt catalysts with cheaper iron catalysts. First attempts with iron catalysts had already been performed in Germany by the Fischer group in the mid 1930s and were then improved by American scientists. F-T in South Africa The next stage in Fischer-Tropsch history was the involvement of South Africa in the 1950s. SASOL (Sasolburg, South Africa) built a coal-based plant (Lurgi dry ash gasifiers) for synthesis gas generation to be used in FischerTropsch synthesis. The SASOL I Fischer-Tropsch plant in Sasolburg had a capacity of 700 000 tons per annum and was iron-based. Due to the oil crisis in the 1970s, SASOL developed the F-T process further and constructed SASOL II and SASOL III at Secunda in the early 1980s. At present, SASOL uses two modes of Fischer-Tropsch operation in South Africa with a combined
12 Quest 7(1) 2011
capacity of 6 000 000 tons per annum, currently the largest production of synthetic fuel and diesel production in the world. The high-temperature (300-350°C) Fischer-Tropsch process (HTFT) with iron-based catalysts based in Secunda is used mainly for the production of gasoline and linear, low molecular mass alpha-olefins, while the low-temperature (200-240°C) Fischer-Tropsch synthesis (LTFT) with either cobalt or iron catalysts is used for the production of high molecular mass linear waxes. A historical perspective of the Fischer-Tropsch process is given in Table 1. Linear alpha olefins are used in the production of polythenes and are important as surfactants in household and industrial detergents. A surfactant is a substance that, when dissolved in water, allows a product such as a detergent to remove dirt from surfaces.
High molecular mass linear waxes are used in many different industries such as rubber, cosmetics, ink and printing, paints and coatings and textiles.
The biggest opportunity for FischerTropsch currently is commercialising natural gas reserves, which can be converted into easily transportable fuels. In 1993, Shell commercialised such a process in Bintulu, Malaysia: the Shell Middle Distillate Synthesis (SMDS). More recently, a gas-to-liquids (GTL) plant in Qatar was commissioned in 2007, which is a joint venture between SASOL and Qatar Petroleum. This plant is currently the largest GTL plant world wide with a capacity of 1 400 000 tons per annum. In contrast to the coal-based Fischer-Tropsch synthesis, this GTL plant runs on cobalt-based catalysts, making it more efficient and environmentally friendly as there are lower CO2 emissions and the products produced are virtually free of sulphur (<5 ppm) and aromatics (<1%). SASOL started with the development of cobalt-based catalyst systems for the Fischer-Tropsch synthesis in the late 1980s and is currently the worldleader in slurry-based cobalt catalyst developments. This is indeed seen as the future of the Fischer-Tropsch synthesis and many more plants using this technology are currently in the commissioning or planning phases, e.g. a SASOL plant in Nigeria and a Shell plant in Qatar.
Reactor development The Fischer-Tropsch synthesis takes place at very high temperatures (up to 350°C) and pressures (10-60 bar). This means that it is critical that the reactors in which the process takes place are designed to work well at these extreme conditions. There are four different types of Fischer-Tropsch reactors, which can be classified into three modes of operation, i.e. fluidised bed, fixed bed and slurry phase (see Figure 2). In fluidised bed reactors the catalyst particles are fluidised by the gas entering into the reactor and the products are produced as a gas (in the gaseous phase). Fixed bed operation requires a stationary catalyst over which the synthesis gas is fed, while the liquid product is drained at the bottom of the reactor. The fixed bed reactors or multi-tubular reactors are designed to contain thousands of individual tubes, which are filled by catalyst particles in the form of pellets or extrudates. Cooling media runs in between the tubes to remove the excessive heat produced by the F-T synthesis process. The combination of catalyst particle size, the size of the tubes and the velocity of the synthesis gas needs to be chosen in a way that gives optimum production. Iron is the preferred catalyst in the fixed bed reactor, rather than the high activity cobalt catalyst, because of the difficulty of controlling the reaction temperature. Five multi-tubular ARGE reactors, jointly developed by two German firms, Ruhrchemie and Lurgi, were installed at the Sasolburg plant in the 1950s. These reactors are 3 m wide, contain 2 050 tubes with a 5 cm diameter, are 12 m in length, and are still in operation today. A fluidised bed reactor uses fused iron catalysts. The high velocity of synthesis gas that enters the reactor suspends the catalyst particles. Typically, the production of gasoline and alkenes is targeted and the reaction takes place at high temperatures. The circulating fluidised bed (CFB) reactor was chosen for the SASOL I plant in Sasolburg in the 1950s (see Figure 3). Later, these reactors were renamed Synthol reactors and were operated successfully for thirty years. The next generation Synthol reactors were
Figure 4. The Oryx GTL plant showing the Fischer-Tropsch synthesis (FTS) section, and synthesis gas generation section which includes the Autothermal Reforming (ATR) plant and the O2 separation facility in Qatar, at night. Image: SASOL
built in Secunda (SASOL II and III) and operated at nearly double its capacity. These reactors are now still in operation in Mosselbay at the PetroSA plant while fixed fluidised bed reactors, called SASOL Advanced Synthol (SAS) reactors, have replaced most of these CFB reactors in Secunda and are currently in operation. In 1989 the first commercial unit was built and demonstrated. This reactor design was a significant improvement over the CFBs in terms of lower cost of construction, increased conversion and lower maintenance intensity. The slurry bed reactor is suitable for the production of wax at low temperature because the wax that is produced acts as the medium in which the fine catalyst particles can be suspended. The liquid product has to be continuously removed from the reactor and this is done using different solid separation systems. Such a system was demonstrated in 1990 in Sasolburg. In 1993, a commercial unit with a 5 m diameter and 22 m high was brought into operation (see Figure 3). The production from one such slurry reactor equalled the production from the five ARGE reactors. Larger-scale slurry bed reactors are possible and the newest additions to the SASOL portfolio of reactors constructed in Qatar (see Figure 4) are producing 35 times as much product as the ARGE reactors A schematic of the reactor production and the development over the years is shown in Figure 3. It is now widely accepted that the slurry bubble column reactor is the preferred reactor type for large-scale plants with a capacity exceeding 40 000 barrels/day. The success of the process relies on operation at very high overall synthesis gas conversions (> 95%), which favours cobalt catalysts. Cobalt catalysts can withstand high water partial pressures, water being the by-product in the FischerTropsch synthesis reaction, while iron oxidises readily to the inactive oxide and is unstable at these conditions. To ensure that the optimum
production is achieved, a number of factors must be considered. Accurate information is required on the hydrodynamics and mass transfer properties. Hydrodynamics refer to the study of the flow and mixing behaviour of the phases (gas/liquid/catalyst) present in fluid bed reactors. SASOL has used 3D simulations of large diameter reactors to provide realistic results that are used in the design of slurry bed reactors, as well as demonstration scale reactors with diameters of up to 1 m to provide realistic data for the design of even larger scale reactors. Proprietary cobalt catalyst development Most of the focus in the early stages (1950-1980s) of Fischer-Tropsch commercialisation at SASOL was on iron catalysts, but by the late 1980s the focus changed to cobalt catalysts in order to convert syngas derived from natural gas into long chain products (wax) in SASOL’s advanced slurry bubble column reactors. The wax would then be hydrocracked in a separate step to produce high-quality diesel and naphtha which is a feedstock for chemicals. The diesel produced in this way is cleaner that conventional diesel. Cobalt metal is about a thousand In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as heavy hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors.
times more expensive than iron ore and to maximise its use and make it more stable against sintering at high temperatures nanometre-sized particles (nanoparticles) are dispersed on support that has a large surface area (see Figure 5). Due to the small size of the cobalt particles advanced techniques such as high-resolution transmission electron microscopy (TEM) are used to characterise and better understand these materials. A lot of effort was put into the design of the catalyst and after around
Figure 3. The development of Fischer-Tropsch reactors and their production utilising cobalt and iron-based catalysts indicating enhanced performance through increased volumetric conversion efficiency. Image: SASOL
Figure 5. High-resolution transmission electron microscopy (TEM) image of a reduced model catalyst showing metallic cobalt nanoparticles on a support. The scale bar represents 10 nanometres. For comparison, the diameter of a strand of human hair is around 60 000 nanometres. Image: SASOL
15 years of development SASOL’s proprietary first-generation cobalt catalyst was successfully applied in the Oryx-GTL plant in Qatar in 2007. Nine decades after its first discovery in Germany, SASOL has demonstrated that there is tremendous growth potential for Fischer-Tropsch synthesis both in terms of reactor and catalyst development. This fact makes Fischer-Tropsch synthesis one of the most promising technologies for the future, and SASOL, with the important development role that it has played since the 1950s, will certainly continue to be at the forefront of the technology for decades to come. ■ Cathrin Welker-Nieuwoudt, Sean Barradas, Denzil Moodley and Philip Gibson are scientists working in SASOL Technology Research and Development’s FischerTropsch Catalysis Research department.
Quest 7(1) 2011 13
Chemistry in South Africa – Mike Booth shows that South Africa has had a thriving chemical industry since the late 1800s.
n a limited sense a chemical industry has been in existence for many centuries. Dyes, fragrances, flavourings and medicinals were extracted from plants, and animal fats were used in soap making and leather preserving. These activities were carried out on a limited scale; just enough was made to meet the immediate needs of small groups of people. Over time some substances, particularly fragrances, dyes and medicinals, became articles of trade and when in short supply, commanded high prices. However, it was not until the Industrial Revolution that chemicals were manufactured in sufficient quantities to talk about a chemical industry as we know it today. Between 1780 and 1840 Britain was transformed from a predominantly agricultural to a predominantly industrial country. Rapid growth in population and urbanisation was accompanied by increased literacy and the need for better housing, clothing, health, food and transport. These changes led to an unprecedented demand for paper, glass, cotton textiles, soap, fertilisers and explosives. Chemists and engineers responded to these demands imaginatively and it was not long before a range of chemicals was being produced. So great, however, was the demand for sodium carbonate and sodium hydroxide that the fledgling chemical industry was often called the ‘alkali trade’. South Africa The chemical industry in South Africa started in 1896, about 100 years after the first lead chamber and Leblanc plants were built in Britain. The discovery of diamonds near Kimberley in 1868, gold on the Witwatersrand in 1886, and coalfields around Witbank and Vryheid, led to a burgeoning mining industry and a rapidly growing demand for explosives. For the first 40 years of its existence the South African chemical industry could well have been called the ‘explosives trade’. In this article the development of the chemical industry is discussed
14 Quest 7(1) 2011
Kimberley seen above the ‘big hole’.
Image: Wikimedia commons
Coalbrookdale at night. An artist’s depiction of the Industrial Revolution in Britain – this shows blast furnaces making light iron through the night. Image: Wikimedia commons
around three major companies, AECI, SASOL and Dow Sentrachem. Omnia has come into prominence more recently. AECI
Alfred Nobel’s discovery of dynamite had made the transportation of nitroglycerine a reality and increasingly large quantities of the explosive were imported into South Africa in the early 1890s. To ensure a regular supply and to improve blasting efficiency, required for mining the hard quartzitic gold-bearing rock of the Witwatersrand, the Nobel Dynamite Trust decided to produce the required explosives locally. And so it was that on 22 October 1896, President Paul Kruger travelled from Pretoria to the farm Modderfontein, east of Johannesburg,
to open De Zuid-Africaansche Fabrieken voor Ontplofbare Stoffen. With a name like this, it is not surprising that the factory was called simply ‘The Dynamite Company’. After the Anglo Boer War of 1899-1902, management of the company passed into the hands of the British South Africa Explosives Company, with the Nobel Dynamite Trust retaining a controlling interest. For some years Cecil John Rhodes, founder of De Beers Consolidated Mines, was concerned about the monopoly on explosives manufacture held by the Dynamite Company. In 1903, one year after his death, the Cape Explosives Works, at Somerset West near Cape Town, started producing dynamite, principally for the De Beers diamond mines around
a long-established industry Kimberley. By 1907 this company’s annual production of 340 000 cases (each of 22 kg) had exceeded that of Modderfontein (230 000 cases). In the UK, Kynoch and Company, Nobel’s chief competitor, had its eye on the rapidly growing explosives market in South Africa. Arthur Chamberlain, who had taken over from the founder, George Kynoch started negotiations with the Natal government in 1907. In an amazingly short period of time, Kynoch established a third dynamite factory at Umbogintwini, south of Durban, in 1909. By 1911 the explosives industry was by far the largest manufacturing industry in the country with an investment of over £2 million and more than 3 000 employees. But three companies all importing the same raw materials, all making the same product, and all using the same process, were finding it difficult to make a profit. Their problems were compounded by the rising price of glycerine; only exports during World War I saved the three companies from bankruptcy. After the war both Somerset West and Umbogintwini diversified into fertiliser manufacture using locally manufactured sulphuric acid and phosphatic rock, most of which was imported from Morocco. The benefits of this development were short-lived; over-production of superphosphate in Holland led to dumping in South Africa. The post-war slump only added to the woes of the industry. Rationalisation was the only answer. African Explosives and (Chemical) Industries
Alfred Nobel’s 1864 application for a patent for nitroglycerine. Image: Wikimedia commons
Adherence to the Montreal Protocol resulted in the manufacture of CFCs being phased out in 1995. The company name was abbreviated to AE & CI in 1972 and, in 1974, a 300 000 ton per annum coal-based ammonia plant was commissioned at Modderfontein. A further name change to AECI followed in 1976 and the company’s dependence on coal as a raw material was emphasised with the commissioning of the Coalplex project at Sasolburg in 1978. A joint venture with Sentrachem, Coalplex consisted of five linked plants: carbide, acetylene, chlorine, vinyl chloride and PVC. Coalplex also produced caustic soda and lime hydrate. During the early 1980s AECI consolidated its position as the major chemical company in South Africa, expanding and diversifying its product range. In 1993 AECI and SASOL agreed to the formation of a new company, later to be called Polifin. This joint venture produces monomers, polymers, chlor-alkali products, cyanide and peroxides. Manufacture of nitroglycerine gave way to new-generation explosives in 1994 and the Modderfontein complex celebrated its centenary in 1996. ▲ ▲
In 1923 Sir Harry McGowan, chairman of Nobel Industries, arranged a merger of their Modderfontein company with that of Kynoch’s at Umbogintwini. Getting De Beers to come on board required more protracted negotiations but success was finally achieved in December 1923 when a new company, African Explosives and Industries, was registered. Mr Ross Frames of De Beers was appointed chairman and Sir Harry McGowan deputy chairman. A young Ernest Oppenheimer, chairman of Anglo American Corporation, joined the board to represent the mining industry and retained a close association with the company for the rest of his life. Two successful mergers in South Africa apparently whet McGowan’s appetite for more in the UK. By 1926
he had formed Imperial Chemical Industries (ICI) from the merger of Nobel Industries, the British Dyestuffs Company, the United Alkali Company, and Brunner, Mond Limited. ICI acquired Nobel Industries’ 50% holding in African Explosives and Industries, establishing a partnership that lasted until 1998. This partnership resulted in a steady flow of technical expertise, information and personnel, which was to be of incalculable benefit in the development of the local chemical industry. The great depression of the early 1930s adversely affected the chemical industry but the board of African Explosives and Industries was looking adventurously to the future. A technical mission from ICI was sent to investigate erecting a synthetic ammonia plant at Modderfontein. In 1932, less than two years later and at a cost of £300 000, the ammonia plant went into full production – 5 000 tons per annum! With an associated oxidation plant it was possible to produce nitric acid and research started into the substitution of ammonium nitrate for nitroglycerine, ultimately with considerable cost savings to the mines. The boom in gold mining meant that expansion of the ammonia plant was inevitable. By 1936 annual capacity had been increased to 25 000 tons. In 1938, Modderfontein and Somerset West together produced 2 348 987 cases of explosives, bringing the total production since 1896 to over 30 000 000 cases. Diversification from explosives followed. Fertilisers, paints, veterinary preparations and insecticides were all produced to meet a growing demand. To reflect this diversity the name of the company was changed to African Explosives and Chemical Industries in 1944. Two years later, as if to celebrate the 50th anniversary of the explosives industry, a calcium cyanide plant was erected, again to meet the growing demand from the gold mines. The next 35 years were characterised by an almost continuous increase in production and diversification. In 1964 the company opened a fourth manufacturing site, the Midland Factory at Sasolburg. Using feedstocks from SASOL the new factory produced initially calcium cyanide and then polyethylene (1966). PVC, chlorinated, fluorinated carbons and chlorinated solvents followed.
Quest 7(1) 2011 15
By 2010, AECI Ltd was composed of African Explosives Ltd (AEL) and Chemical Services the speciality chemicals arm with a portfolio of 20 independent businesses focused on defined markets. SASOL Although SASOL started producing oil from coal in 1955 its origins can be traced back to 1895 when coal was first mined on both sides of the Vaal River near Vereeniging. The mining house, Anglovaal, was interested in the large deposits of low-grade coal in this area and further south in the Free State. There was considerable interest in coal chemistry during the 1920s, and in 1927 a Government White Paper was published recommending the development of gasification and carbonisation processes. In the early 1930s, Anglovaal and the British Burmah Company established the South African Torbanite Mining and Refining Company (SATMAR) to mine oil shales near Ermelo, to distil off and refine the oil, mainly for petrol. Anglovaal’s interests in oil-fromcoal were extended when rights to
The code that appears on high-density polyethylene products to indicate that they can be re-cycled.
Coal – still a major source of energy generation in South Africa. Image: Wikimedia commons
16 Quest 7(1) 2011
A fossil found in oil shale in Germany.
Image: Wikimedia commons
the German Fischer-Tropsch process were acquired. In 1938 Hendrik van Eck, Anglovaal’s consulting chemical engineer, appointed Etienne Rousseau as research engineer at SATMAR to pursue this initiative. Franz Fischer visited South Africa in 1938 to assist in getting the venture off the ground. However, World War II intervened. During the war Anglovaal maintained its interest in oil-from-coal and entered into negotiations with the MW Kellogg Corporation. There was considerable interest in the USA at that time, with the US Government considering an oil-from-coal plant on the west coast. In 1945 Anglovaal applied to the SA Government for assistance to establish a plant based on the American Hydrocol process. After protracted negotiations a licence was finally issued in 1949. Because of devaluation and involvement with gold mining developments, Anglovaal needed assistance to raise the required £20 million. The World Bank expressed polite interest in the project but no money was forthcoming. In the meantime negotiations were proceeding with the Kellog Corporation for licensing of its patents and assistance in the design and erection of a plant. However, Rousseau believed that a closer look needed to be taken at what the Germans had been doing with the Fischer-Tropsch process since the war. He obtained an offer from the Lurgi Gesellschaft, Oberhausen-Hollen, and Ruhrchemie Aktiengesellschaft, through an Arbeitsgemeinschaft (ARGE), of the designs for and the right to operate plants for the production of synthesis gas from coal and the Fischer-Tropsch process.
The upshot was the establishment, on 26 September 1950, of the Government-sponsored South African Coal, Oil and Gas Corporation Ltd., commonly called SASOL. This acronym arose from Rousseau’s initial suggestion that the company be called South African Synthetic Oil Limited. Rousseau, SASOL’s first employee, was appointed managing director, a position he held for 18 years. Both Kellog and ARGE processes were used; the former produced high proportions of medium octane petrol, LPG, and a range of chemicals; the latter produced mainly higher boiling waxes and oils, including diesel. The plant, and its associated town, Sasolburg, were established in the Free State, just south of the Vaal River. After some difficulties in the early years, SASOL chemists and engineers managed not only to get the plant working satisfactorily but also to devote time to improving efficiency and to widening the product range. Feedstocks for the manufacture of synthetic rubber, fertilisers and secondary chemicals followed. Together with Total SA and the National Iranian Oil Company, a refinery (NATREF) was established in Sasolburg in 1960. Imported petroleum was refined and cracked to produce ethylene for plastics, and pipeline gas was supplied in increasing quantities to industry. SASOL II and III
Before World War II, coal provided more than two-thirds of the world’s energy needs. By 1973 oil provided more than half of these needs, consumption was increasing and the first oil crisis threatened supplies from the Middle
factors, ranging from prolonged droughts through high interest rates to increased international competition, had an adverse impact on Sentrachem’s profitability. These, together with the decline in the value of the rand, left the company in a vulnerable position. At this point the Dow Chemical Company made a bid for Sentrachem and took control in 1997.
Sheets of synthetic rubber coming off an early plant.
East. SASOL’s response to these developments was to commission a feasibility study on the establishment of a second oil-from-coal plant. At the end of 1974 plans for the erection of SASOL II were announced at a cost of R2 458 million. A site about 100 km to the east of Sasolburg, to be called Secunda, was chosen. Construction began in 1976 and was completed in 1980. At that time, South Africa imported much of its oil from Iran and the overthrow of the Shah precipitated a further oil crisis. The result was SASOL III, constructed in 1982 adjacent to SASOL II. Since its inception SASOL has always placed a high priority on research and development. The SASOL I plant no longer produces fuels but instead a wide range of chemicals that include ethanol, normal butanol, ethyl acetate, acrylic acid and butyl acrylate. The establishment of a downstream chemical cluster production facility at Sasolburg, named Chemcity, using products from Sasol I was started at the beginning of this decade. The Fischer-Tropsch process has undergone continuous improvement – see the Fischer-Tropsch Process: generating synthetic fuels – in this issue. Two recent acquisitions, that of German chemical firm Condea and SASOL’s increased stake in China’s Condea Naijing Chemicals to 100%, are evidence of the company’s continued globilisation strategy. The SASOL group of companies remains focused on sustainable growth through a strategy comprising five primary elements: business renewal and continuous improvement; joint ventures and alliances; innovation; focused investment in
Image: Wikimedia commons
existing business and new valueadded chemical projects. Dow Sentrachem In 1967 National Chemical Products (NCP), the Industrial Development Corporation (IDC) and Federale Volksbeleggings (FVB) pooled their chemical interests into a single entity, Sentrachem, which became the Sentrachem Group. When Sentrachem was launched in 1967 its four constituents were NCP, Kolchem, KOP and SRC. The new board, which was chaired by Etienne Rousseau of SASOL, initiated an ambitious expansion programme, which included several joint projects with companies such as Uniroyal, Hoechst SA and Olin Corporation. Production included rubber chemicals, high density polyethylene and polypropylene. The joint venture with Olin Corporation led to the formation of Aquachlor, which produced chlorine-based water sanitisers. The acquisition of Agricura, a formulator of insecticides and herbicides, provided an entry into agricultural chemicals. Subsequently called Agrihold, this company manufactured crop protection products, animal feeds and a range of veterinary products. Besides being a primary manufacturer, Sentrachem became involved with downstream converting through a group of companies operating under the control of Mega Plastics. In 1993 Delta G Scientific was acquired, signalling a new emphasis on research and development. This was designed to assist Sentrachem to move out of commodity chemicals into high value-added products. During the 1990s a number of
The rise of the Omnia Group During its 100 years of existence, the development of the chemical industry has been dominated by three factors: the demand for explosives by the mining industry, the abundance of relatively cheap coal, and the political and regulatory environment in which it operated between 1948 and 1994. Based in a country with no proven oil reserves, until recently little natural gas and abundant coal resources, it is not surprising that the gasification of coal became a major factor in the development of the industry. This was aided and abetted by a political system that increasingly forced the industry to look inwards and to focus on import replacement. It led also to the construction of small-scale plants with production geared to local demand. As a consequence locally produced commodity chemicals and processed goods have generally been less than competitive in export markets. For a developing country, South Africa has an unusually large chemical industry and it is of substantial economic significance. In 2011 the industry still contributes 5% to the GDP and 25% of manufacturing sales. The Omnia Group has become a major player in recent times and is today a diversified, specialist chemical services provider with its business interests balanced across the chemical, mining and agricultural markets. Now that South Africa is once again part of the international community, the chemical industry is focusing on the need to be internationally competitive and is reshaping itself accordingly. Exports were R49 billion and imports R95 billion in 2009. Rationalisation in some sectors of the industry, as pointed out in this article, has been drastic. However, signs that the industry is leaner and more competitive are clearly apparent. ■ Dr Mike Booth is the Director: Information Resources, Chemical and Allied Industries Association.
Quest 7(1) 2011 17
Green chemistry: from the chemical industry to everyday life The chemical industry has traditionally been regarded as ‘dirty’. Green chemistry is the industry’s response to environmental protection. Liliana Mammimo explains how this happens.
A typical chemical plant.
Image: Wikimedia commons
18 Quest 7(1) 2011
reen chemistry is the way in which chemists have responded to the environmental problems that have been generated by many aspects of the production and use of substances, and the rapid growth of the chemical industry in the last two centuries. Given the essential role of chemistry for development, green chemistry is thus the chemists’ contribution to the efforts aimed at making development sustainable: Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Green chemistry uses chemical knowledge to make the production of substances cleaner and the use of substances safer. The earlier definitions, such as the one adopted by the IUPAC Working Party on ‘Synthetic Pathways and Processes on Green Chemistry’, focused strongly on safety, viewing green chemistry as: The invention, design and application of chemical products and processes to reduce or to eliminate the use and generation of hazardous substances. The need to protect the environment is closely linked to the need to protect
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their desired function while minimising their toxicity. n Safer solvents and auxiliaries. The use of auxiliary substances--solvents, separation agents, and others--should be made unnecessary wherever possible and should be harmless when used. n Design for energy efficiency. Energy requirements of chemical processes should be recognised for their environmental and economic impacts and should be minimised. If possible, synthetic methods should be conducted at normal temperature and pressure. n Use renewable feedstocks. A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable. n Reduce derivatives. Unnecessary derivatisation − use of blocking groups, protection/deprotection, and temporary modification of physical/chemical processes − should be minimised or avoided if possible, because such steps require additional reagents and can generate waste. n Catalysis. Catalytic reagents (as selective as possible) are superior to stoichiometric reagents. n Design for degradation. Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment. n Real-time analysis for pollution prevention. Analytical methods need to be further developed to allow for real-time, inprocess monitoring and control prior to the formation of hazardous substances. n Inherently safer chemistry for accident prevention. Substances and the form of a substance used in a chemical process should be chosen to minimise the potential for chemical accidents, including releases, explosions, and fires. ■
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Professor Liliana Mammino is at the University of Venda. She carries out research on biologically active molecules. NORTH-WEST UNIVERSITY YUNIBESITI YA BOKONE-BOPHIRIMA NOORDWES-UNIVERSITEIT
Quest 7(1) 2011 19
Innovation through diversity ™
BLACK KHAKI 082012/R
human health, as environmental pollution has negative impacts on human health, ranging from comparatively mild (such as irritations of the airways) to serious and even lethal (e.g. when the pollutants are carcinogenic). Green chemistry aims at preventing environmental pollution: Green chemistry focuses on the design, manufacture and use of chemicals and chemical processes that have little or no pollution potential or environmental risk and are both economically and technologically feasible. If we think of the huge number of substances that are commonly used in everyday life, and of the amount of research needed to make the production of each of them as clean as possible, it is easy to work out the huge size of the tasks facing green chemistry. Green chemistry in South Africa Green chemistry research is active in a number of centres in South Africa. On the other hand, green chemistry is still poorly covered in school and university chemistry courses and general information to the public is still inadequate. People need to be made aware of its importance for industrial development and for consumers’ attitudes. The green chemistry principles – a set of ‘sound housekeeping’ principles The twelve principle of green chemistry are: n Prevention. It is better to prevent waste than to treat or clean up waste after it has been created. n Atom economy. Synthetic methods should be designed to maximise the incorporation of all materials used in the process into the final product so that there is no waste. n Less hazardous chemical syntheses. Wherever practical, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment. n Design safer chemicals. Chemical products should be designed to effect
• The vision of the NWU’s Potchefstroom Campus (NWU Pukke) is to become a research-directed campus where excellence in both teachinglearning and research are mutually reinforcing. • The North-West University (NWU) is an innovative institution, offering research in a structured and multidisciplinary environment organised into 22 research entities. This focused approach adopted by the NWU has resulted in increased research performance over a number of years. • An atmosphere of creative thinking is conducive to a strategy of expanding the NWU Pukke’s current fields of expertise or areas that are identified of being of critical importance. • High profile intellectuals differentiate, identify and distinct the activities of the NWU Pukke in delivering Masters, Doctorate and post-doctoral fellows that is complementary to other research nationally,
The International Year of Chemistry Global Experiment Big Splash – Cape Town, 22-25 March 2011 Rovani Sigamoney tells QUEST about a global experiment to celebrate the International Year of Chemistry.
O Learners enthusiastically carry ouf the ‘Big Splash’ experiment. Image: © R. Sigamoney/UNESCO
How to do it.
Image: © R. Sigamoney/UNESCO
Image: © R. Sigamoney/UNESCO
20 Quest 7(1) 2011
n the occasion of UN World Water Day, 22 March 2011, UNESCO and IUPAC launched the International Year of Chemistry (IYC) Global Experiment (the ‘Big Splash’). This event occurred at Ratanga Junction, Cape Town from 22-25 March 2011 and was organised in collaboration with the City of Cape Town Municipality. The IYC Global Chemistry Experiment (entitled ‘Water: A Chemical Solution’) consists of four component activities: pH measurement, salinity measurement, filtration/disinfection, and desalination. Each can be carried out by children of all ages in schools around the world and no special equipment is needed (all experiments can be done with laboratory equipment at schools). The activities are adaptable to the skills and interests of students of various ages and use equipment that is widely available. The theme for UN World Water Day 2011 was ‘Water for Cities: Responding to the Urban Challenge’. The week of the Big Splash also coincided with the South African National Water Week and thus the learners were exposed to different activities that emphasised the importance of water in their city, Cape Town. Learners from different schools in Cape Town (areas such as Langa, Khayelitsha, Hout Bay, etc) were firstly exposed to the difficulties of obtaining water from a standpipe in Khayelitsha (an informal settlement). This activity taught the learners the hardships faced daily by people in informal settlements as well as how they cope. They were then transported to Ratanga Junction where they watched a delightful play performed by Jungle Theatre, which taught them the importance of conserving and preserving their local water supplies.
Thereafter the learners eagerly completed two of the four experiments for the IYC Big Splash with the expert supervision of Erica Steenberg from RADMASTE Centre, University of Witswatersrand, and three volunteers. The participating learners enthusiastically found the pH of a sample of water from Intaka Island (a wetland in Cape Town) and thereafter filtered and purified the water. This was the first chemistry experiment that most of the learners had ever carried out and their excitement at completing the exercise and obtaining the results was delightful to witness. Their total engagement in the experiment was evident in the many questions that they asked. The Department of Science and Technology in South Africa generously donated IYC Global Experiment kits to the schools that attended the Big Splash as the schools lacked the equipment to conduct the experiment. In a brief opening ceremony on 22 March 2011, presided over by UNESCO, the Deputy Minister of Science and Technology, Mr. Derek Hanekom, presented the schools with their kits for the IYC Global Experiment. SASOL also sponsored the event and provided the learners with caps, which were elatedly accepted. The International Year of Chemistry activities are also supported by global partners Dow and the European Petrochemical Association (EPCA) and global sponsors BASF, L’OREAL Foundation-UNESCO For Women in Science, CEFIC, SOLVAY and EVONIK Industries. ■ Rovani Sigamoney is Assistant Programme Specialist, Basic and Engineering Sciences, UNESCO. For more information on the Global Water Experiment visit http://water.chemistry2011.org
Understanding natural products and their uses requires an understanding of their chemistry. Siegfried Drewes gives a historical perspective.
Figure 1. Major regions of plant diversity and endemism in South Africa.
atural products are compounds synthesised in nature – in this case we will talk only about compounds produced by plants. All plants produce primary metabolites (nucleic acids, proteins, sugars and fats) which are used as fuels. However, plants also produce secondary metabolites that are not essential for the life of the plant, although they serve other useful purposes. A primary metabolite is a (usually small) molecule that is produced by metabolism. Metabolism is the set of chemical reactions that occur in living organisms to maintain life. A secondary metabolite is not directly involved in these processes, but usually has an important function.
Early research (1895 – 1949) When, and for what reasons, did our original researchers call upon nature to reveal these ‘most remarkable things’? First, remember that three of the richest floristic regions in Africa occur in the southern subcontinent. These are the Cape Floristic Region, the Maputaland-Pondoland Region and the Succulent Karoo Region. In addition there are several smaller regions that are also rich in plants (Figure 1). There are around 30 000 species of plants in southern Africa. Not only are our indigenous plants used for decorative (proteas) and commercial (black stinkwood and tamboti furniture) purposes, but some 3 000 species are also used as medicines, mostly by traditional healers. Unfortunately, because
Figure 2. Scilla natalensis Figure 3. Tribulus terrestris
around 35 000 – 70 000 tonnes of plant material are consumed each year some plants are close to extinction. The late 1800s and early 1900s are the years when the use of natural products as medicines took shape. At this time two industries were the mainstay of economic growth in South Africa. These were gold, which had been discovered on the Witwatersrand in 1884, and agriculture in the form of maize, wheat and related products, together with extensive stock farming.
Some plants give off poisons to keep predators away, others use brightly coloured pigments to attract insects for pollination, and still others make compounds that may be used to treat human illnesses. Drugs used to treat malaria are a good example – quinine and artemisinin are both derived from plants. In fact, some 50% of all commercial medicines are derived either directly from plants, or are modifications of plant products. The indigenous medicinal plants of South Africa (muthi plants) are currently being investigated by
researchers to look at their use in treating serious illnesses. A prominent organic chemist, and natural products researcher, Friedrich Wöhler, back in 1835, wrote ‘Organic chemistry just now is enough to drive one mad. It gives the impression of a primeval tropical forest, full of most remarkable things, a monstrous and boundless thicket, with no way to escape, into which one may well dread to enter.’ South African researchers have taken up this challenge in a vigorous fashion as will be shown as the story unfolds.
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Figure 4. The structure of geigerin.
Research into anti-cancer compounds from the indigenous Combretum caffrum tree The compound combretastatin (Figure 6) was first isolated from the root bark of the indigenous tree Combretum caffrum (bush willow) in the early 1980s by a researcher called Pettit. Subsequently other constituents were isolated, the most active one being combretastatin A-4. Two of Pettit’s coworkers at the Arizona State University were Gordon Cragg and Margaret Niven, both students from South Africa. In 2010 Dr Cragg was awarded an Honorary doctorate by Rhodes University.
Figure 6. Structures of combretastatin and combretastatin A-4. At present combretastatin A-4 (water-soluble as a phosphate derivative) is the most potent naturally occurring combretastatin known. It has been shown to cause disruption to the blood supply of tumours in cancer patients and Phase III clinical trials are currently underway.
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Figure 5. The carbon NMR spectrum of hypoxoside.
However, agriculture was plagued by severe stock-diseases, which led to the death of thousands of cattle and sheep in the years 1890 to 1929. Poisonous plants grazed by the animals gave rise to illnesses with very descriptive names such as ‘slangkop poisoning’ (due to Scilla natalensis and related Scilla species (Figure 2), ‘stywe siekte’ (caused by Crotolaria burkeana), ‘geel dikkop’ (due to ingestion of devil’s claw, Tribulus terrestris, Figure 3) and ‘vermeersiekte’ (the result of eating the plant Geigeria aspera). The latter plant led to the death of a million sheep in 1929. These diseases, coupled with the earlier ‘rinderpest’ epidemic (late 1890s), which killed not only cattle and sheep, but also decimated veld animals such as buffalo, giraffe, eland and kudu, placed a great strain on veterinarians and medical personnel. Research into the chemistry of these poisons started at the Onderstepoort Veterinary Research Institute, which became known world-wide as a result. An important area of research was into the toxic component of the ‘gifblaar’ (Dichapetalum cymosum), highly toxic to sheep, with an LD50 of 0.25 – 0.50 mg/kg (sheep). This work was carried out by Dr JSC Marais, who found that the toxic compound was monofluoroacetic acid (CH2FCO2H), the first record of a fluorinated compound in nature. The LD50 is the dose that kills half the animals tested.
One of the last remaining mysteries of the above era was to find the active component in Geigeria aspera which caused ‘vermeersiekte’. This turned
out to be a compound called geigerin, which is shown in Figure 4, which was discovered in 1957 by Professor Guido Perold then at the National Chemical Laboratory of the CSIR, and colleagues from Imperial College, London. However, not all the research was carried out by recognised researchers in academic institutions. Dr Jotello Festiri Soga, the son of the Rev Tiyo Soga, was quietly applying his medical and indigenous knowledge helping rural farmers in the Eastern Cape with the cattle diseases rife in that area. He was the first black South African to qualify as a veterinary surgeon (in Edinburgh, Scotland) and worked as district veterinarian in the Cape Colony in the late 1800s and early 1900s. He showed that the illness krimpsiekte, that affects sheep and goats, is caused by poisons in the plant Tylecodon ventricosis. Enter technology Between 1950 and 1990 natural products research changed drastically. During this time, nuclear magnetic resonance spectroscopy (NMR), highresolution mass spectrometry (MS) and high-pressure liquid chromatography (HPLC) were used to identify the active ingredients in natural products. A typical carbon-13 NMR spectrum, for example, hypoxoside from the African potato, is shown in Figure 5. Each peak represents a different carbon atom, each in its own unique chemical environment. At the same time, the focus of research changed from animal diseases to human disease. Researchers in both conventional and traditional medicine are investigating the use of natural products to treat HIV and AIDS – so
Q History of science
Hoodia gordonii Sutherlandia frutescens
far with little success. However, malaria is another story. The first successful drug against malaria was quinine, which was first extracted from the bark of a South American tree. But, the malaria parasite has become resistant to quinine in many areas and it is another product derived from Artemisia annua, artemisinin, that is now being used with success against malaria. Where are we now? In spite of all the knowledge accumulated from the study of South Africa’s indigenous flora, no singlecomponent, commercially marketable drug has emerged from this country. Now is a good time to re-assess the situation and consider future prospects. Any compound or extract that hopes to compete on the open market should meet with at least three of the following criteria: 1. The chemistry must be wellestablished. 2. The biological activity, whatever its nature, needs to be beyond doubt. 3. It would be advantageous if the mother plant was amenable to largescale cultivation. 4. If cultivation is not an option as a result of low yields, then a synthetic procedure must be in place. 5. The whole system should be under patent protection. Initiatives that meet at least three of these criteria are:
1. The product, or group of products, isolated from Sutherlandia frutescens. 2. Vasorelaxant pyrano-isoflavones from the shrub Eriosema kraussianum. 3. The compound known as ‘rooperol’ from Hypoxis hemerocallidea as an indicator of malignant cells in breast cancer. 4. The appetite suppressant from Hoodia gordonii which promised so much initially, but has fallen somewhat ‘flat’. It needs a second look. 5. Antibacterial substances with good activity against a variety of bacterial infections. The genus Helichrysum is a particularly rich source of these chemicals and this applies to a lesser extent to some compounds from Warburgia salutaris and Gunnera perpensa. 6. Marine products derived from a variety of plants and animals. None of this current research would have been possible without the pioneering work of many people over the past few decades, all of whom worked long and hard to put South Africa on the map in terms of research into natural products. ■
Hypoxis species Eriosema kraussianum
Professor Siegfried Drewes is an Emeritus Professor and Honorary Research Associate in the School of Chemistry, University of KwaZulu-Natal, Pietermaritzburg. He has been researching the chemistry of muthi plants for countless years.
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Hoodia is normally a relatively sparsely distributed plant.
An appetite suppressant agent from Hoodia, developed by CSIR scientists, promises to become the first natural food ingredient for weight management based on a plant indigenous to the African continent. By Vinesh Maharaj.
From plant to production: the Hoodia story S
outh Africa has a long history of natural products chemistry, typically based on the investigation of the biological properties of the chemical components isolated from indigenous plants, often to find the reasons for livestock losses after ingestion of toxic plants (see Natural Products in South Africa: a brief history, in this edition). Indigenous plants have always formed part of the diet of communities in rural areas. During the early sixties, an investigation was launched by the National Food Research Institute of the CSIR to determine the nutritional value and also any possible long-term toxic effect of ‘food from the veld’. The Hoodia research programme, which was part of this investigation, already spans over 40 years at the CSIR, and has yielded both direct and indirect benefits and is still ongoing. 1963 saw the start of a series of processes that led to the creation and protection of intellectual property,
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licensing to commercial partners and the benefit-sharing agreement with the San people, custodians of indigenous knowledge on the use of Hoodia. The botany of Hoodia Plants belonging to the Hoodia Sweet ex Decne. genus are perennial, succulent plants indigenous to the arid regions of southern Africa occurring only in South Africa, west Namibia, Botswana, Zimbabwe and south west Angola (Albers and Meve, 2002). They are commonly called ‘stapeliads’, which are fleshy stem-succulents belonging to the Ceropegieae tribe of the subfamily Asclepoadoideae of the family Apocynaceae, previously the Asclepiadaceae family (Bruyns, 2005). The Hoodia genus contains 13 species, all of which have an upright and thorny shrub habit. In earlier botanical history, the Hoodia genus and the Trichocaulon genus were recognised as two distinct plant genera. More recently a single Hoodia genus has been proposed (Bruyns, 2005).
Historical use of Hoodia as a source of food and water Hoodia plants have been used traditionally as a source of food and water by the indigenous people of southern Africa. The first documented use dates back to the nineteenth century when Hoodia pilifera was reported to have been eaten by indigenous people to quench their thirst (Pappe, 1862). The plant was also reported to be used as a substitute for food and water (Marloth, 1932) and Trichocaulon plants are reported to be edible in the raw state or preserved in sugar (White and Sloane, 1937). H. pilifera, of which there are two sub-species, H. pilifera subsp. pilifera and H. pilifera subsp. annulata, is a small spiny shrub limited to southern regions of the Western Cape and Eastern Cape Provinces of South Africa. It is called ‘ghaap’, ‘guaap’ or ‘ngaap’ by indigenous people. In contrast, H. gordonii is more widely distributed across summer rainfall regions of Namibia into the Northern
Laboratory extraction of plant material.
Cape and Western Cape Provinces of South Africa. Where it occurs, it is usually a common plant forming extensive colonies of robust, spiny shrubs. H. gordonii is apparently not eaten as often as H. pilifera; its lingering and bitter taste has given the plant the name ‘muishondghaap’ or ‘jakkalsghaap’. However, in spite of this, because H. gordonii is more abundant, is larger and grows faster it was selected as the species on which to focus development.
Appetite suppression: the breakthrough The semi-pure fractions that were generated were biologically assayed in the laboratory using a rat model. The semi-pure fractions of the extract that showed appetitesuppressant properties in the animal model were separated into several A biological assay, or bioassay, is used to measure the effects of a substance on an animal. Bioassays are used in the development of new drugs or when monitoring environmental pollutants. The procedure is used to estimate the potency or nature of a substance by looking at its effects on living matter.
individual components using repeated chromatographic separation and repeated testing in the animal model. Eventually the breakthrough was made and the active ingredient was isolated and identified (van Heerden et al, 2007). The compound, a steroidal glycoside (see Figure 1) had the remarkable ability to reduce the food intake of laboratory animals, and to make them lose weight as a result. The results of this stage of the investigation were as exciting as the original observation in 1963: a new chemical entity was discovered, representing a family of molecules with newly discovered appetitesuppressant properties. Now the scientists needed to know what dose was effective and safe. To do this, they administered female rats five doses of the compound carried in potato starch over three days and gave a control group of female rats potato starch only. The rats were monitored over eight days. Figure 2 shows that the
Preparing for processing.
Breaking the plant down to start the extraction process.
Laboratory analysis of plant extracts.
Scientific innovation CSIR scientists who first studied the biological effects of extracts of this plant on small laboratory animals noticed that the animals lost their appetite, accompanied by a loss of weight, with no apparent toxic effects. This was 1963, the first, scientifically validated observation of appetite suppression caused by extracts derived from Hoodia. The following six years saw attempts by leading CSIR scientists to isolate and identify the chemical substance responsible for the appetite suppressant effect of extracts of the Hoodia plant. However, the range of chromatographic and spectroscopic techniques available to chemists and biochemists during the sixties simply was not sufficient to allow progress. The project was moth-balled from about 1970. During 1983, twenty years after the Hoodia research started at the CSIR, the organisation acquired state-ofthe-art nuclear magnetic resonance spectrometry (NMR) to use for the identification of chemical structures of complex natural products. This provided the stimulus to re-launch the investigation of the appetite suppressant properties of the Hoodia plant. The main task at this stage was to isolate the active compounds in extracts of the Hoodia plant. To do this, the extracts had to be separated and then purified
using chemical analytical techniques such as column chromatography.
Quest 7(1) 2011 25
Figure 1. The chemical structure of a steroidal glycoside.
Table 1. Hoodia research – the sequence of events 1997
The CSIR and Phytopharm, a UK Biotechnology company, entered into a joint agreement to develop H. gordonii into a prescription medicine for the management of obesity. Much of the expertise and technology for developing prescription medicines did not exist in South Africa and one of the main purposes of the agreement was to transfer this expertise to South Africa.
The CSIR publishes its Bioprospecting Policy, guaranteeing sharing of benefits with owners of indigenous knowledge.
Phytopharm signed a licensing agreement with Pfizer Inc. for the development and commercialisation of H. gordonii, in which Pfizer acquired an exclusive worldwide license for the sale of a prescription pharmaceutical for obesity. Significant progress was made during the collaboration, culminating in the successful completion of a clinical trial in 2001 to evaluate the safety, tolerability, pharmacokinetic profile and effect on calorie intake of an extract of H. gordonii. Following the closure of Pfizer’s Natureceuticals group in 2003, Pfizer discontinued clinical development and returned the rights to Phytopharm.
2002-2003 The CSIR signed a benefit-sharing agreement with the indigenous San people in which a proportion of any milestone payments and royalties from product sales will be paid into a San Hoodia benefit-sharing trust. This agreement is still in place and is heralded as a flagship benefit-sharing arrangement, one of the first of its kind in the world. 2004
The global interest in Hoodia plants increased following the patenting and subsequent licensing agreements. To ensure the survival of wild plant populations in the face of threats of unregulated harvesting, all Hoodia species were listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Since 2005, the international trade of any Hoodia material has required CITES permits that are issued by the national conservation authorities of the southern African countries.
Phytopharm entered into a joint development agreement with Unilever PLC in December 2004. Unilever was granted an exclusive global license to H. gordonii extract. The staged research and development programme completed extensive non-clinical and clinical studies with a view to bringing H. gordonii extract to the market as a functional food, clinically shown to suppress appetite and capitalising upon the non-clinical work prior to their licensing deal with Phytopharm.
Unilever discontinues development.
The CSIR signed a cooperation agreement with Phytopharm in November 2010, for the further development and commercialisation of Hoodia for the management of obesity. In terms of this agreement the commercialisation process will be led by the CSIR in collaboration with national and regional stakeholders, and has the full support of the South African San Council.
Figure 2. The effect on body mass. Dosage on days 1,2,3 given in 6.25, 12,25, 25, 37.5 and 50 mg/kg/day.
Figure 3. The effect on food consumption. Dosage as in Figure 2.
rats reduced their rate of mass gain, and in some cases, even lost weight, while taking the active compound. At the same time, they reduced their intake of food (Figure 3). This suggests that the compound reduced appetite. This combination of reduced food intake and reduction in mass gain was found even at the lowest doses (6.25 mg/ kg). The rats all remained healthy during the period of the study.
26 Quest 7(1) 2011
These preliminary tests using the compound containing the steroidal glycoside indicated that the molecule has significant appetite-suppressant activity and also results in decreased body weight when consumed orally over a three day period. Filing the patent – where are we now? The CSIR continued development of Hoodia and filed a patent to protect
its invention of a novel method of obesity control. The sequence of events that followed is shown in Table 1 and highlights how some key issues were addressed. The Hoodia research programme spans 40 years at the CSIR and is still ongoing. The programme has already yielded both direct and indirect benefits. Based on the international success of Hoodia, South Africa’s
Benefits of licensing The estimated market size for new weight-management agents is in excess of US$ 3 billion per year. It can be reasonably expected that the commercial production of the active extracts will provide an opportunity to establish a sizable local manufacturing business. The licensing of Hoodia ensured full involvement of South African scientists in the development programme, which allowed capacity building with the transfer of state-of-the-art phyto-medicine production technology to South Africa. This technology is based on the manufacturing of herbal extracts in compliance with Good Farming and Manufacturing Practices (GMP) as approved by the international regulatory bodies. The potential for royalty revenue through the licensing of the patented technology, and milestone payments linked to clinical trials are also direct financial benefits of licensing.
Cultivation of Hoodia.
Table 2. Challenges and lessons learnt Challenge
It was extremely difficult to operate in a policy vacuum.
Policy development benefits from real-life case studies (learn on the run).
Due to the long time from project idea to There should be more active participation commercial success it is difficult to determine of all parties throughout the at what stage of the product development development cycle. cycle must benefit-sharing agreements be signed with owners of traditional knowledge. Contracting when revenue/benefits to parties are uncertain and linked to outcome of clinical trials while managing high expectations is difficult. Communication ‘burden’ is part of operating in an interdependent world – sheer number of partners, handling the different needs and expectations of parties.
Better communication tools for different stakeholders and parties.
Traditional knowledge has intrinsic value but requires significant value addition through technology/marketing to realise its value.
Promotion of science and technology for value addition of traditional knowledge.
Genetic resources are common to more than National participation required across one country while access to these resources has borders. to be balanced against national and regional claims. Man-made versus cultural and biodiversity cross borders makes national agreements very difficult. Balancing trade secret/knowledge and protection with transparency.
scientific innovation capacity is now globally recognised. Challenges and lessons learnt During the Hoodia development programme and negotiation of benefits with the San people, the parties involved were faced with various challenges and key lessons were learnt. A summary of these are shown in Table 2. Conclusions The appetite suppressant from Hoodia developed by CSIR scientists illustrates the value of combining modern science and ancient knowledge for the use of South Africa’s rich biodiversity. Hoodia also illustrates the potential of bio-prospecting to produce significant economic and social benefits for a nation, including the owners and
Regular meetings, sharing of information relationship building with knowledge holders.
holders of indigenous and traditional knowledge. Hoodia’s further development as a food ingredient for weight management is being reviewed and the true benefits will be realised once a legitimate, efficacious and safe product is on the market. The ongoing bioprospecting activities of the CSIR have produced a rich portfolio of drug candidates, including potential new treatments for diseases such as malaria, HIV, asthma, diabetes and inflammation. The further development of these candidates benefit substantially from the product development platform that resulted from the Hoodia research programme. ■ Dr Vinesh Maharaj is Research Group Leader, CSIR, Biosciences in Pretoria.
In anticipation of a successful outcome of clinical trials, the CSIR has entered into a benefit-sharing agreement with the San people. This agreement is possibly one of the first examples of its kind anywhere in the world. The guiding principles that led to the agreement are the following: ‘Both parties commit themselves to the conservation of biodiversity by, inter alia, applying legal “best practices” with the collection of any plant species for the observation, and by ensuring that no negative environmental impacts flow from the proposed bioprospecting collaboration.’ ‘The CSIR acknowledges the existence and the importance of the traditional knowledge of the San people, and the fact that such body of knowledge, existing for millennia, predated scientific knowledge developed by Western civilisation over the past century.’ Under the agreement, the CSIR will pay the San people 8% of all milestone payments it receives from its licensee, UK-based Phytopharm, as well as 6% of all royalties that the CSIR receives once the drug is commercially available. The potential monies will be paid into the San Hoodia Benefit-sharing Trust with representation including one CSIR trustee, one South African representative from the Department of Science and Technology, three San trustees (#Khomani, 1Xun and Khwe) of South Africa, San trustees representing San communities of Angola, Namibia and Botswana, one San trustee representing WIMSA and one legal representative of the San people. The agreement will remain in force for the royalty period for as long as CSIR receives financial benefits from the commercial sales of the products. All record keeping is done jointly by the CSIR and the San Trust. Other benefits include existing the CSIR study bursaries and scholarships available to the San community and agreement on future bioprospecting for the benefit of both parties.
References 1. Albers F, Meve U. Illustrated Handbook of Succulent Plants: Asclepiadaceae. Springer, 2002: 1-318. 2. Bruyns P. Stapeliads of Southern Africa and Madagascar. Hatfield, South Africa: Umdaus Press, 2005: 1-329. 3. Pappe L. A description of South African Forest Trees and Arborescent Shrubs Used for Technical and Economical Purposes. 2nd ed. Britain: Ward and Co., 1862. 4. Marloth R. The Flora of South Africa with Synopsis of the South Afican Genera of Phanerogamous Plants, vol. III. London: Wheldon and Wesley, 1932. 5. White A, Sloan B. The Stapelieae, vol. III. Pasadena: Abbey San Encino Press, 1937. 6. Van Heerden FR, Marthinus HR, Maharaj VJ, Vleggaar R, Senabe JV, Gunning PJ. An appetite suppressant from Hoodia species. Phytochemistry 2007; 68: 2545-2553.
Quest 7(1) 2011 27
Research that can change the world
Impact is at the core of the CSIR's mandate. In improving its research focus and ensuring that it achieves maximum impact in industry and society, the organisation has identified six research impact areas: s Energy - with the focus on alternative and renewable energy. s Health - with the aim of improving health care delivery and addressing the burden of disease. s Natural Environment - with an emphasis on protecting our environment and natural resources. s Built Environment - with a focus on improved infrastructure and creation of sustainable human settlements. s Defence and security - contributing to national efforts to build a safer country. s Industry - in support of an efficient, competitive and responsive economic infrastructure.
Analytical techniques in chemistry A
nalytical techniques in chemistry are split into qualitative and quantitative techniques. Qualitative means that you work out what something is, quantitative means that you also work out how much. Here are a few examples of each type.
Qualitative techniques Flame test Qualititave anlysis often requires very simple apparatus, such as a Bunsen burner. You may have done flame tests at school. These are used to show the presence of certain metal ions. The ions have different colours because they all emit different frequencies of electromagnetic radiation. The flame test shown is on sodium carbonate and the characteristic colour is that of sodium. Copper gives a blue-green colour and iron turns gold in a flame. Mass spectroscopy Another qualitative analytical technique is mass spectroscopy. This method of looking at the composition of a substance measures the relative proportions of isotopes or molecules in the substance using a mass spectrometer. This means that it is also a quantitative technique. The substance under investigation is turned into vapour, which is then passed over high-energy electrons that ionise the substance. These are then accelerated across a magnetic field, which deflects the ions of different masses by different amounts. Finally an ion detector is able to detect the amount of deflection of each isotope or molecule and so provide information on the composition of the substance under investigation. Nuclear magnetic resonance (MNR) spectroscopy This method is used the investigate the position of atoms in a molecule. Radio waves are passed through a sample of a substance that is held between the poles of a magnet. The amount of absorption shows the position of particular atoms within a molecule. The information is given in a graph called a nuclear magnetic resonance spectrum.
Quantitative analysis There are many different types of quantitative analysis, such as volumetric analysis, using titration, and gravimetric analysis and chromatography. Volumetric analysis Volumetric analysis, which you may know as titration, is a way of determining the concentration
A diagram of a burette.
Image: Wikimedia commons
of a solution. One solution is added to another using a burette, which is a calibrated glass tube, from which a solution is slowly dropped into a conical flask that contains a measured volume of the second solution. The first solution is added to the burette until the end point is reached, which is when all the second solution has reacted. The end point is detected by using an indicator. The volume of the solution that is needed to reach the end point is called the titre â€“ this is read from the calibrations on the burette. You can then calculate the concentration of the solution. Gravimetric analysis This is a way of determining the amount of a substance that is present by converting it into another substance whose chemical composition is known and that is easily purified and weighed. For example, gravimetric analysis can be used to measure the amount of lead in a sample of water containing a lead salt. In this process, potassium dichromate is added to a known volume of water. A yellow precipitate (solid) is formed that is removed by filtering. The precipitate is then crushed and dried and weighed accurately. The concentration of the lead in the sample of water is calculated from the volume of water, the weight of the lead chromate and relative atomic mass of lead. Chromatography Chromatography is a very common type of quantitative analysis. This involves separating small amounts of substances from a mixture using the rates at which they move through or along a medium, for example an absorbent paper like blotting paper. Most methods of chromatography involve dissolving the mixture in a solvent â€“ called the eluent. However, in gas chromatography the substance is vapourised. Substances move at different rates because they have different degrees of solubility in a particular medium. There are different types of chromatography. Column chromatography was the technique used by the CSIR scientists when they were extracting the active ingredient in the Hoodia plant. In column chromatography the components in the mixture are separated in a column that contains a solvent and a material that attracts molecules. â–
A flame test on sodium carbonate. This is an industrial test and the flame is viewed through cobalt glass. Image: Wikimedia commons
A mass spectrometer in use.
Image: Wikimedia commons
A nuclear magnetic resonance spectroscope. Image: King Saud University
1: Column loaded with silica/column medium. 2: Eluting solvent added to compact silica layer and to remove air bubbles. 3: Purple mixture as a thin layer is added to top of silica layer. 4: Eluting solvent added and eluted (purple layer separates into a red and blue layer). 5: Eluting solvent added and eluted (red and blue layers separate further). 6: Red layer collected (the faster-moving layer). 7: Blue layer collected (the slower-moving layer). 8: No more compounds are eluted, process ended.
An example of black ink separated into its component colours using paper chromatography. Image: Wikimedia commons
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the key to biodiversity conservation Nature Reserve
Figure 1. An ecological network (EN) at Good Hope forestry estate and an adjacent nature reserve in the Midlands of KwaZulu-Natal. Large-scale natural grassland ENs allow species to move beyond the borders of the nature reserve through commercial forestry areas. Image: Lize Joubert
Figure 2. (A) Large, circular patches have a larger proportion of core habitat than (B) smaller habitat patches or (C) habitat patches with irregular shapes. Habitat quality is higher in core (central) areas than in edge zones.
The principles for developing ENs ■ Habitat patches outside reserves should be as large as possible ■ Habitat patches should be interlinked as much as possible ■ Linkages between habitat patches should be as wide as possible ■ Habitats should be as varied as possible ■ Habitat quality throughout the EN should be as high as possible ■ Edges should be as soft (gradual) as possible ■ Natural disturbance regimes should be simulated as closely as possible
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iodiversity is the variety of all life. It has value to humans because it provides products (e.g. honey and medicinal plants) and services (e.g. water purification and pollination) that underpin life as we know it. Over the last 150 years, human actions have caused declines in the abundance of many species. Such declines can lead to local species extinction. To prevent such population declines and local extinctions, we need to put mitigation measures in place. Among such measures are large-scale ecological networks (ENs). ENs are systems of landscape linkages that connect natural habitat patches in the commercially productive landscape with nature reserves (Figure 1). ENs provide habitats for many species, while also allowing movement of mobile species. Thus, natural habitat in ENs functions as a ‘home’ to some species and as a ‘road’ to others. In South Africa, the forestry industry, particularly Mondi, is setting standards for EN development by leaving about one-third of the plantation landscape unplanted. This area is predominantly indigenous forest, grassland and wetland habitat, but also includes fire breaks and homestead areas.
Ecological Networks have been proposed as a way to mitigate biodiversity loss caused by anthropogenic land use. Lize Joubert and Michael J. Samways share guidelines for developing ecological networks using experience from the South African forestry industry. Formulating guidelines for developing ENs in commercial landscapes was based partly on research conducted on invertebrate species in the ENs among forestry plantations. Invertebrates are sensitive to changes in the landscape and have relatively fast, measurable responses. Five main development guidelines were identified: 1 identify and maintain large natural habitat areas outside formally protected nature reserves, 2 identify a backbone of high-quality habitat patches in which natural disturbance regimes are simulated, 3 link isolated high-quality habitat patches with each other and, if possible, with nature reserves, 4 incorporate a wide range of quality habitat types (i.e. habitat heterogeneity) and 5 consider ecosystem processes that are associated with the spatial dispersal of species across the landscape (e.g. processes associated with mountains and rivers). Patch size and edge effect Generally, large areas of natural habitat have higher habitat quality than small areas of natural habitat. This is partly because of the edge effect, i.e. the effect of management practices in commercial land that borders natural habitat patches. For butterfly and grasshopper communities in natural grassland ENs, the edge effect of forestry plantations
stretches 30 m beyond the plantationgrassland boundary. The proportion of natural habitat that is not influenced by edge effect is known as the core area. A very large, circular habitat patch has the highest proportion of core habitat (Figure 2). Research has shown that natural grassland ENs with a diameter of more than 200 m have sufficient core (central) habitat to function as ‘home’ for butterflies, even though this grassland habitat patch is bordered on two sides by commercial forestry plantations. For this reason, it is better to conserve large habitat areas with large core areas than small habitat patches with little or no core area. Edge effect can be ‘softened’ by replacing straight boundaries between plantations and natural habitat with curvilinear ones (Figure 3), as was done in the north of KwaZulu-Natal at SiyaQhubeka Forests adjacent iSimangaliso Wetland Park. Here, curvilinear boundaries traced wetland edges, which were defined by occurrence of hydromorphic soils. These soils represent important hydrological processes and the conservation of water. Plantations were cleared from wetland areas, as part of a wetland delineation programme aimed at improving hydrology of the St. Lucia Lake, a World Heritage Site renowned for its natural value.
Include a wide range of quality habitat types Different types of natural habitat are characterised by different suites of biological species. In the broadest sense of the word, a ‘habitat’ provides food, water, safety and opportunities for reproduction (i.e. a place to live and survive) to plants, fungi and animals. There are four vegetation types (grassland, thicket, wetland and indigenous forest) in association with ENs. However, there are a whole range and many gradations of habitat types within a single vegetation type. Grassland in different positions in the landscape (e.g. hilltop and valley floor), with different aspects (e.g. north and south-facing slopes) or on different substrates (e.g. rocky, sandy and clayey) are home to different suites of species (Figure 6). The inclusion of different habitat types in ENs not only increases the number of species that live in that landscape but also presents opportunities for species to move around to survive adverse conditions. There is a delicate balance between including as many habitat types as possible and securing the size of each habitat type. Each habitat type should be large enough to retain functionality, that is, it should be able to support ecological interactions that are common to that habitat type (e.g. herbivory, predation, pollination) and maintain minimum viable population sizes of key invertebrate species. It is better to include a few functional habitat types than many dysfunctional habitat types in ENs. ▲ ▲
Establish a backbone of highquality natural habitat Habitat quality is a measure of the extent to which the habitat has remained in its natural state. While habitat quality can be maintained by simulating natural disturbance regimes and controlling alien invasive species, it is very difficult to improve habitat quality once an area has been overgrazed or intensively colonised by alien invasive plant species (e.g. bramble, guava, black wattle and bug weed). Funds allocated to conservation should finance conservation initiatives that will contribute most to regional conservation objectives. Therefore, maintaining high-quality habitat should have higher conservation priority than restoring low-quality habitat (Figure 4). Nevertheless, once a high-quality area has achieved prime conservation status, it can then be strategically expanded to include larger areas.
Reduce isolation of habitat patches Conservation corridors are linear strips of natural habitat that link high-quality natural habitat in the commercial landscape with each other and with nature reserves. They facilitate movement of species from one nature reserve through the commercial landscape into other nature reserves and thus allow species to expand their ranges beyond the borders of a single nature reserve. Increased movement between populations of the same species reduces the danger of local extinctions and inbreeding depression for populations in previously isolated habitat patches (Figure 5).
Figure 3. At SiyaQhubeka Forests in the north of KwaZuluNatal, curvilinear boundaries were established between eucalypt plantations and natural habitat in ENs as part of a wetland delineation programme. Wetland edge areas were based on occurrence of hydromorphic soils. Image: Lize Joubert
Figure 4. Overgrazing in communal land reduces habitat quality. These degraded areas should not, in the first instance, be included in ecological networks.Image: Lize Joubert
Isolated forest patch Plantation
Figure 5. Conservation corridors alleviate isolation of natural habitat patches by linking them to each other and to nature reserves. Ideally, this isolated patch of forest habitat at SiyaQhubeka Forests in the north of KwaZulu-Natal should be linked to the main body of forest habitat in the foreground, by removing a small section of the plantation. Image: Lize Joubert
Quest 7(1) 2011 31
Plantation Protea community
A practical example of an EN that was designed according to these principles
Figure 6. Inclusion of a wide range of habitat types in ENs increases the number of species that could potentially live in and pass through that landscape. This section of the EN at Good Hope forestry estate in the Midlands of KwaZuluNatal includes rocky outcrops, slopes with different aspects, streams, hilltops and valley floors. Image: Lize Joubert
Figure 7. For maintaining natural processes, it is essential that ENs include the natural variety of topographic types. Shown here is Norwood forestry estate in the Midlands of KwaZulu-Natal, where an EN was designed around a river catchment area. Image: Lize Joubert
Consider key ecosystem processes ENs need to be effective at maintaining natural ecosystem processes, with conduits, such as streams, low-lying areas such as wetlands, and high points such as hills and cliffs all being important (Figure 7). These landscape elements generate processes responsible for spatial arrangement of biodiversity across the landscape, all essential for long-term biodiversity conservation. Different aspects of ENs are being investigated actively investigated in the Department of Conservation Ecology and Entomology, Stellenbosch University, with sponsorship from Mondi. Researchers work in close collaboration with the forestry industry to find solutions to environmental problems. â– Lize Joubert is a PhD student at the Dept of Conservation Ecology and Entomology (Stellenbosch University). She is part of the Mondi Ecological Networks Programme (MENP) where she explores practical solutions to real life conservation problems in transformed landscapes. Michael Samways is Professor and Chair of the Dept of Conservation Ecology and Entomolgy, Stellenbosch University. His research is mainly aimed at designing landscapes for the future.
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An EN was designed at SiyaQhubeka Forests (Ltd), adjacent to iSimangaliso Wetland Park, according to principles mentioned above. Plantations on hydromorphic soils were cleared and rehabilitated back to grassland/wetland habitat. These recovered grassland/ wetland areas, together with mown grassland firebreaks, connect high quality forest, thicket and grassland habitat patches to allow free movement of animals from the nature reserve through plantations. A recent study compared grassland habitat in this EN with similar habitat in a nature reserve. It was found that ENs and the adjacent nature reserve generally conserved a similar collection of plant species where their disturbance history in terms of fire and grazing were similar. A parallel study is also being undertaken at higher elevations in the Midlands of KwaZulu-Natal to investigate the degree to which ENs among forestry plantations represent biodiversity found in nature reserves. These results are paving the way for further implementation of ecologically sound ENs in other parts of South Africa, among agriculture as well as commercial forestry. Right: Here, field assistant Lea Ezzy records dung and tracks of animals that passed through this part of the ecological network. Image: Lize Joubert Below and right: White rhino, elephant, hippopotamus, giraffe, leopard, blue wildebeest and zebra are just some of the large mammal species that utilise ecological networks among commercial forestry plantations. Some of these large mammals, in turn, can alter the natural environment to make it more suitable for other species to live in. For example, here, dung beetles use dung from a white rhino midden on the edge of a young eucalypt plantation. Image: Lize Joubert
STUDY CHEMISTRY AT THE FACULTY OF SCIENCE, UNIVERSITY OF JOHANNESBURG ... IT MAY CHANGE YOUR LIFE OUR RESEARCH FOCUS IS ON | CATALYSIS WITH EMPHASIS ON SYNTHETIC METHODOLOGIES | BIOCATALYSIS | SPECIATION ANALYSIS AND WATER TREATMENT | THE DETERMINATION OF MOLECULAR STRUCTURE | NANOMATERIALS WE ALSO OFFER UÊÊÕ`iÀ}À>`Õ>ÌiÊ>V>`iÞÊÜ iÀiÊ«ÀÃ}ÊV iÃÌÀÞÊÃÌÕ`iÌÃÊ}iÌÊÌ iÊ««ÀÌÕÌÞÊÌÊ `ÊÀiÃi>ÀV Ê>}Ã`iÊ«ÃÌ}À>`Õ>ÌiÊÃÌÕ`iÌÃÊUÊ*>ÀÌiÀÃ «ÊÜÌ Ê-ÌÊ`ÀiÜÃÊ1ÛiÀÃÌÞÊÊÊ -VÌ>`]ÊÌ ÀÕ} ÊÜ V ÊÜiÊvviÀÊ>Êi`Ê* Ê«À}À>iÊÊ iÃÌÀÞÊUÊ£ää¯ÊLÕÀÃ>ÀÞÊ«ÕÃÊ ,xäääÊvÀÊÌ«Êi>ÀiÀÃÊÊÃViViÊUÊ/ iÊ } iÃÌÊµÕ>ÌÞÊvÊi`ÕV>ÌÊ>ÌÊ>ÊiÛiÃ UÊÊV«Ài iÃÛiÊÀ>}iÊvÊ`i}ÀiiÃÊ>`Ê`«>ÃÊUÊÌiÀ>Ì>ÞÊ>VVÀi`Ìi`ÊµÕ>wV>ÌÃÊ UÊ7À`V>ÃÃÊÀiÃi>ÀV Êv>VÌiÃÊUÊ/«ÊÌV Ê>V>`iVÃÊÜÌ Ê } ÊµÕ>ÌÞÊÀiÃi>ÀV ÊÕÌ«ÕÌ UÊ"««ÀÌÕÌiÃÊvÀÊV`ÕVÌ}Ê}ÀÕ`LÀi>}ÊÀiÃi>ÀV Ê
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Cameras and sound: new approaches Alistair Becker shows how scientists can use cameras and sound to â€˜seeâ€™ fish.
A healthy shallow seagrass bed in the Bushmanâ€™s Estuary.
Image: Alistair Becker
Example of emergent reeds (Phragmites australis) within the East Kleinemonde Estuary.
34 Quest 7(1) 2011
Image: Alistair Becker
stuaries form some of the most scenic and popular destinations along our coastline, however, they also play an important role in the life cycle of many species of fish. They are some of the most productive ecosystems on the planet and provide a rich source of food for fish inhabiting these areas. Because of this they are also ideal places for juvenile fish to develop and grow to maturity. As such, estuaries have been recognised as important nursery grounds. Many marine fish species spend the juvenile phase of their life within estuaries including garrick (Lichia amia), white steenbras (Lithognathus lithognathus), kob (Argyrosomus japonicus) and blacktail (Diplodus capensis). A closer look at almost any estuary will reveal that these systems are actually made up of a variety of habitats which together form a patchwork creating the broader estuarine landscape. Depending on your location, such habitats may include seagrass, mangroves, sandy areas, mud banks, emergent macrophytes, rocky reefs, deep water channels or salt marsh. Fish ecologists have spent much effort trying to untangle the roles each of these different habitats plays for fish inhabiting estuaries and usually use various nets to catch the fish within the habitat being studied. This works well in simple habitats (such as sand, mud and deeper channels) but becomes difficult when the habitat is highly structured, such as rocky reefs or emergent macrophytes. Catching fish with nets also only provides us with data on the abundance of the different species within the habitats and tells us little of how the fish utilise the different habitat types. In order to begin to fill this knowledge gap, together with Professor Alan Whitfield and Dr Paul Cowley, of the South African Institute for Aquatic Biodiversity (SAIAB), I set about investigating the use of new methods and technology in a number of projects within estuaries along the Eastern Cape.
in the study of estuarine fish
Underwater camera and tripod stand ready to be deployed in the East Kleinmonde Estuary. Image: Alistair Becker
Seagrass beds exposed during low tide in the Bushman’s Estuary.
shoaling species such as the estuarine roundherring (Gilchristella aestuaria). Interestingly, while the numbers and species were similar among sand and rocky reefs, when we turned our attention to the behaviour of the fish we found some clear differences. Over bare sand the fish tended to form tight, rapid-swimming schools, while within reefs they were more often seen slowly swimming around and feeding on occasion. From this we think that the fish move rapidly through the open sandy areas of the estuary, but once they are among the more structured reef habitat they spend more time slowly swimming and foraging for food. This was an important finding. It showed for the first time that two habitats, which have similar fish communities within estuaries, are clearly being used in different ways and this should be considered by scientists when studying estuarine habitats and their potential as nursery areas. We are now also conducting another project using underwater cameras, this time in the tidal Bushman’s Estuary near Kenton. This project is similar to the one carried out last year in East Kleinemonde except this study is focusing on patches of seagrass and comparing the fish assemblages again to bare sand. However, because the mouth of the Bushman’s Estuary is always open, the system is a little more dynamic
Estuaries are often turbid – this green coloured water is not uncommon in Eastern Cape estuaries. Image: Alistair Becker
and there are big changes as the tide comes in and then flows back out again. The aim of this study will be to compare fish assemblages among sand and seagrass and see if the assemblage changes as the water level rises while the tide comes in. Using sound to ‘see’ fish Underwater cameras work well in studying fish when the water is clear, but estuaries are more often than not, turbid environments. While the camera work in East Kleinemonde was useful, the study was limited to the lower reaches of the estuary where the water was clear. We wanted to know how the fish were distributed along the length of the estuary and if their behaviour changed in different sections of the system. In addition we wanted to see which species of fish were moving ▲ ▲
The first project involved using an underwater camera to record fish assemblages which are associated with rocky reefs, emergent reeds (Phragmites australis) and bare sand within the clear waters of the East Kleinemonde Estuary. The mouth of the estuary was closed throughout the study, which is a common feature of many South African estuaries. This involved mounting an underwater video camera on a small tripod and positioning it either in the reef, reeds or bare sand and filming for an hour. The images collected by the camera were recorded onto a shore-based video recorder connected to the camera via a cable. This process was completed five times in three replicate patches of reef, sand and reeds, resulting in 45 hours of video footage. This allowed us to see what fish species were entering the habitat and also what they were doing while in the habitat. The underwater camera was also useful because it allowed us to position the camera in small isolated patches of habitat that would be difficult to investigate using traditional netting techniques. We found that there were similar numbers of fish within each of three habitats. However, the species making up these numbers within the reeds differed from those within the reefs and sandy areas. Mullet were more common in reef and sandy areas while in the reeds we frequently saw small
Image: Alistair Becker
Quest 7(1) 2011 35
The shore-based equipment required by the DIDSON was placed in a boat so that we could easily move it between sites. Image: Alistair Becker
A diagram showing how the acoustic camera was deployed and orientated within the estuary. Dashed lines represent the area imaged by the camera.
into a shallow flooded wetland after dark. Unfortunately, underwater cameras were not going to allow us to collect this information. So, in collaboration with scientists from Norway, we arranged the use of a high-tech piece of equipment called a Dual frequency IDentification SONar (DIDSON), also known as ‘acoustic cameras’ as they produce near-video quality images from underwater using sound. You can think of them as being very sophisticated fish finders, but are actually more like an ultrasound. They emit 96 beams of sound (up to 70 m long) through the water and form a high resolution image from the sound that is bounced
36 Quest 7(1) 2011
back. What makes them so special is that they can create up to 21 highresolution images per second, enough to create free-flowing videos. More importantly, because the DIDSON uses sound, not light, to create videos, they can be used in turbid waters and at night with no reduction in image quality. While the DIDSON is positioned to ‘look’ horizontally through the water column (see the diagram) the image it creates is that of a ‘bird’s eye view’ (i.e. from above looking down). The resolution at shorter ranges (about 10 m) allows for features such as fins and the beating of the tail to be easily seen. We positioned the DIDSON at
sites along the length of the East Kleinemonde estuary to study the size structure, distribution and behaviour of fish during the day. While the resolution of the images was not sufficient to identify fish to species we could easily measure their lengths with specific software and so could place fish into four size classes. Smaller fish (100 – 300 mm) were most abundant and were common along the whole length of the estuary. We found that large predatory fish (> 500 mm) were most common near the estuary mouth, as was their main prey, the small shoaling species (Gilchristella aestuaria and Atherina breviceps). We also found that smaller fish (almost certainly mullet between 100 - 300 mm) were more likely to form schools in sections of the estuary where the water was less turbid, and this schooling behaviour was even more common when large predatory fish were also present. While there is still much footage to process (we collected over 150 hours!) it appears that DIDSONs represent an exciting new method in studying estuarine fish. The application of these new methods in the study of estuarine fish allows us to better understand how fish interact with the different habitats within estuaries as well as other fish. This understanding will help scientists and managers to look after and preserve estuaries and the fish within them for everyone to enjoy. ■ Dr Alistair Becker received his PhD in 2007 from Deakin University, Australia. He has worked as a post-doctoral fellow at the South African Institute for Aquatic Biodiversity since 2009 after being awarded a Claude Leon Foundation Fellowship. His research interests focus on the association of fish assemblages with habitats in coastal zones and how this fits with our current understanding of nursery grounds and habitat fragmentation. Professor Alan Whitfield is the Research Manager and Principal Aquatic Biologist at the South African Institute for Aquatic Biodiversity (SAIAB). He has over 30 years of research experience working on South African estuaries. Dr Paul Cowley is a Principal Aquatic Biologist at SAIAB. His research spans estuarine ecology and the tracking of fish within estuaries as well as along the coastline of South Africa.
Right: Two identical visual outputs from the DIDSON with the static background (substrate) present (A) and the background removed (B). The output provides a ‘bird’s-eye view’ of the fan shaped sector illuminated by the DIDSON, scale is in metres horizontally away from the DIDSON. A school of mugilids (between 200 and 300 mm) is highlighted, their acoustic ‘shadow’ can be clearly seen in image (A). A group of small shoaling species (< 100 mm) can also be seen in image (B) once the background has been removed.
DIDSON in operation in the East Kleinemonde Estuary.
Image: Alistair Becker
The DIDSON The DIDSON was developed by the University of Washington’s Applied Physics Laboratory and was designed to be used by the US Navy for underwater surveillance and uses lenses that focus returning sound beams to create high resolution images. It became available to the scientific community around 2003. It operates in two frequency modes: a low frequency mode (1.0 MHz) which can be used at ranges of 50 -70 m, but produces poor resolution images. In high-frequency mode (1.8 MHz) the range is reduced to about 10 m. However, the images are at a much higher resolution. The DIDSON ‘looks at’ a fan-shaped arc across a 29º horizontal plane and 14° vertical plane. The 29° arc is broken up into 96 separate horizontal beams, 0.3° in width and 14° high. The beams themselves are composed of 512 longitudinal ‘bins’. So each image is formed from 96 x 512 ‘data values’. The longer the range the more stretched each of the 512 bins will be, resulting in lower resolution. The DIDSON works best when it is positioned still and aimed so the sound beams just skim across the bottom which allows fish swimming in the water to be easily seen. Scientists have used the DIDSON to count salmon migrating up rivers in the northern hemisphere, to check the effectiveness of by-catchreducing devices on commercial fishing gear and to study fish under ice. This is the first time one has been used in South Africa and also the first time one has been used to study fish in small closed estuaries which are common across the southern hemisphere.
For more information: Becker, A, Cowley, PD and Whitfield, AK. Use of remote underwater video to record littoral habitat use by fish within a temporarily closed South African estuary. Journal of Experimental Marine Biology and Ecology 2010: 391: 161-168.
SOUTH AFRICAN INSTITUTE FOR AQUATIC BIODIVERSITY SAIAB is a research facility of the National Research Foundation (NRF) and is an internationally recognised centre for the study of aquatic biodiversity. SAIAB houses the National Fish Collection, hosts the largest library of books and journals on aquatic and ichthyological topics in Africa and is a leader in modern biodiversity data management. SAIAB is renowned for the historical discovery by Professor JLB Smith, of the long-believed extinct coelacanth. Built on the legacy of this discovery, SAIAB houses world-famous collections of marine fishes from the Atlantic, Indo-Pacific and Antarctic Oceans, as well as freshwater fishes from Africa and adjacent islands. The collections include frogs, invertebrates, otoliths and diatoms. SAIAB promotes research excellence for the sustainability of African aquatic environments through major national and international research programmes in Conservation Biology & Ecology and Molecular Biology & Systematics. Contact us to find out more: Somerset Street, Grahamstown Email: firstname.lastname@example.org Web: http://www.saiab.ac.za .saiab.ac.za Find us on Facebook too
Quest 7(1) 2011 37
Drought in Africa has led to serious land degradation. Image: Wikimedia commons Flooding in Australia caused chaos in towns.
The Burnett River, Australia, in flood.
Image: Wikimedia commons
Image: Wikimedia commons
A satellite image of the flooding in Queensland.
Image: Wikimedia commons
Scorched, frozen or flooded! What’s happening to the weather? Mike Lucas and Mathieu Rouault ask if the current extreme weather events of drought interspersed with flooding are a sign of climate change.
mages of sun-scorched and withered maize crops, hard-baked and cracked soils devoid of vegetation, near-empty dams and reservoirs, as well as starving people and livestock are all too frequent in Africa. Drought in the austral summer 2010 was particularly severe, especially in the Sahel region of the Sahara, and in Zimbabwe. The spectre of global warming seemed all too real, and indeed, the general trend of global warming has continued as CO2 concentrations have continued to rise at unprecedented rates. Yet by late 2010 and in early 2011, global weather patterns in many places went haywire! Tropical cyclones caused deluges of rainfall and extensive flooding in south-eastern Brazil, Sri Lanka, Pakistan and in Australia. After the floods in New South Wales in early December 2010, the ‘Sunshine State’ of Queensland was hit by Tropical Storm Sasha on Christmas Day, when localised rainfall in the Cairns region was as much as 400 mm in a single day! The resulting floods devastated about 10%
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of Queensland (which covers nearly two million km2), destroying one of their main export crops, sugar cane. Queensland also produces and exports most of Australia’s coal, but the floods put a stop to all mining activity. More than 200 000 people were affected by the calamity, which is estimated to have cost Australia about one billion Australian dollars. South Africa did not escape the deluges either. In January 2011, torrential rainfall in the Orange River catchment area in the north-east of the country caused the Orange River to rise and flood large areas around Upington, including the Augrabies Falls. Losses to agriculture and infrastructure were estimated at more than R100 million. The pattern was clear. Everywhere in the southern hemisphere, the eastern coastlines of South America, Africa, Asia and Australia were experiencing almost unprecedented rainfall and floods in a latitudinal band between the Tropic of Capricorn to about 30°S. Meanwhile in early December 2010,
much of the northern hemisphere, including Canada, the USA, the UK and Europe was experiencing some of the worst winter weather in decades. Images of snow-blizzards and snowcovered cars leapt out at us on our TV screens. In Scotland and in the northeast of England, snow-falls of 40-70 cm were recorded in the first week of December. In remote country villages throughout Britain, many families were trapped in their homes for 10 days or more. December 2010 was the coldest since 1890, and over the whole year, 2010 was the 12th coldest over the last 100 years; although it was drier and sunnier in the west of the country. On average, London (Heathrow airport) was about 5 °C colder than the average for the period 1971-2000. But what was the cause of such extreme weather? The unusual conditions in December were due to cold polar airflow from the Arctic and Greenland, rather than the more usual warmer but wetter westerlies. Not surprisingly, the chaotic weather
Q Climate change
Left & above: The flood waters at the Augrabies falls. Image: kruger.com
patterns have fuelled the climate change debate, polarising opinion and beliefs. Climate change sceptics point to frozen Europe as evidence that global warming is a myth, while images of scorched and drought-ravaged Africa in 2009/10 reinforce the global warming lobby. So what on earth is happening to climate and weather patterns? Climate and weather Before answering this, we need to distinguish between climate and weather. Climate represents a broadly regional condition that is typical, such as ‘temperate’ (for example the UK), ‘equatorial’ (e.g. central Africa), ‘Mediterranean’ (e.g. Cape Town) or ‘polar’ (e.g. the Arctic and Antarctica). Such climate regimes often experience seasonal variability (e.g. winter/summer) and long-term climate change over centuries or more. However, weather is what we experience daily. It is local and changeable over periods of hours, days, weeks or longer; for example seasonal weather patterns. However, weather patterns can also be subject to global modification over inter-annual or decadal time-scales. One such modification we experience is due to El Niño and La Niña events.
El Niño and La Niña The term El Niño, meaning ‘the boy’ (Christ-Child) in Spanish, was coined by Peruvian fishermen in 1975 to describe the appearance of unusually warm water that occurs every three to six years along the western South American coast at about Christmas time. Now, El Niño events more broadly describe warming of the central and eastern equatorial Pacific, which reduces the atmospheric pressure gradient between the eastern and western Pacific. The associated fluctuation in tropical sea level pressure in the eastern and western Pacific is known as the Southern Oscillation, so
that El Niño events form part of the broader coupled ocean-atmosphere phenomenon known as the El NiñoSouthern Oscillation, or ENSO. In normal (La Niña) years, easterly trade winds blow right across the surface of the equatorial Pacific from Peru/Chile to Indonesia in the western Pacific basin. Apart from helping to set up coastal upwelling off Peru, these winds also create general divergent open-ocean upwelling right across the eastern half of the equatorial Pacific. This sets up a surface temperature gradient of less than 20 °C in the east to more than 30 °C in the west, resulting in a shallow thermocline in the east, but a much deeper one in the west. The prevailing trade-winds also ‘pileup’ water in the west where ocean levels are several centimetres higher than in the east. Off Peru and Chile, local along-shore winds drive coastal upwelling that brings nutrient-rich water to the surface, resulting in a diatomdominated phytoplankton community that supports the well-known and profitable anchoveta fishery. By contrast, El Niño Southern Oscillation (ENSO) events are associated with anomalous warming of the central and eastern equatorial Pacific on average every three to five years, although fossil records indicate that it used to follow a decadal pattern. El Niño, the opposite of La Niña, occurs when easterly trade winds lose intensity, allowing warm water from Indonesia and eastern Australia to flood eastwards across the Pacific, ‘capping’ upwelling waters of the general equatorial and coastal Peru/ Chile upwelling regions (see El Niño conditions). This raises surface temperatures in the eastern equatorial Pacific to as much as the 29 °C. Surface ocean warming deepens the ocean’s
A satellite image of the snow blanketing Ireland. Image: Wikimedia commons
Power lines brought down by an ice storm in extreme weather conditions. Image: Wikimedia commons
Quest 7(1) 2011 39
Global average rainfall differences during the mature phase of the 2011 La Niña in austral summer (D, J, F) relative to average rainfall (D,J,F) for the years 1988-2000. Blue/green is wetter than normal, yellow/red is dryer than normal. Intense blue patches over Brazil, South Africa and Indonesia show where the floodproducing rainfall fell. Floods in western Australia occurred in December, due to a westward movement of the intense rainfall visible to the east of the country.
Global average sea surface temperature differences (SST) during the mature phase of the 2011 La Niña in austral summer (D, J, F) relative to average SST’s (D, J, F) for the years 1988-2000. Orange is warmer than normal, blue is colder than normal. Images: Mathieu Rouault
thermocline, depressing it by as much as 90 metres. This sets up the requirement for substantial wind energy to erode and mix the stratified surface layer. However, local upwelling-favourable coastal winds have insufficient energy to do this, so the nutrient-impoverished surface layer results in a dramatic loss in phytoplankton productivity, resulting in a collapse of the anchoveta population. Within the coastal upwelling region, there are high rates of mortality among top predators and a collapse of the fishery. During the 1997/98 El Niño event, overall fish stocks declined by about 50%, resulting in revenue losses to Chile and Peru of about $8 billion. With changes in sea surface temperature (SST) across the Pacific, atmospheric pressure cells in the east and west Pacific are reversed, with high pressure in the western Pacific and low pressure in the eastern Pacific. Changes in atmospheric pressure in turn cause the Pacific cell ciruclation – called Walker Cell atmospheric circulation - to shift eastwards. As a result, rainfall patterns shift across the Pacific and Indian Oceans, and extreme weather conditions may occur in surrounding continents, causing droughts in normally wet areas, while heavy rains and flooding may occur over normally arid regions. The subtropical Hadley Circulation and westerly storm tracks are also modified. Curiously, however, El Niño events do not always result in anomalous weather events for reasons that we do not yet properly understand. However, the extreme rainfall and flooding events witnessed in Australia
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and in South Africa were not caused by El Niño, but by stronger than usual La Niña patterns. The 2010/2011 La Niña La Niña, meaning ‘the girl’ in Spanish, is the climatic opposite of El Niño, and it is the strong La Niña of 2010/2011 that has caused the extensive flooding in Brazil, South Africa and Australia. But how exactly does this work from a South African perspective? During La Niña events, the Indian and Pacific Oceans cool by several degrees, while the influx of moistureladen air from the Indian Ocean region south of Madagascar into the eastern and central part of South Africa strengthens, leading to rainfall. Water vapour condenses, releasing heat, which warms the air, which in turn lowers the pressure of the continental Low Pressure atmospheric system over southern Africa. The resulting increase in the pressure gradient between ocean and land increases the intensity of the south easterly upwelling-favourable winds on the west coast, while strengthening the the intensity of rain-bearing wind along the south and east coast. This results in increased summer rainfall and an increase in frequency of extreme weather events, such as tropical cyclones. The natural seasonal cycle is modulated, and westerly storm tracks shifted southwards, which is why the western Cape was much drier than usual in early 2011. However, during El Niño events, atmospheric pressure rises above normal over southern Africa, preventing rainfall and shifts westerly storm tracks
north, causing weaker, less frequent SE winds, reducing upwelling along the west coast (Benguela region). Further afield, the 2010 La Niña favourably strengthened India’s southwest monsoon, but contributed to the floods in Brazil, Australia and Sri Lanka described earlier. The 2010 La Niña, combined with record high ocean temperatures in the north-eastern Indian Ocean, was the cause of the Queensland floods, and was also responsible for the heavy snowstorms in North America, the UK and Europe in December 2010. The last previous strong La Niña episode occurred during 1988–1989, while weaker ones formed in 1995, in 1999– 2000, and from mid 2007–2009. Climate change, ENSO and weather Climate change is a long-term process, where regional or local cooling does not imply that global warming is a myth. Rather, ENSO events and variable weather patterns impose their own unique signal on top of the climate change signals. Whether climate change will amplify or moderate extreme weather patterns is the subject of some debate, but it does appear that extreme weather events will become more common and more intense, such as tropical cyclones. This is not surprising, because as the oceans warm up, they impart more heat and energy into the atmosphere, which fuels the intensity of tropical cyclones. As the oceans warm, they also lose more moisture to the atmosphere by evaporation, which precipitates as rainfall above the ocean. This increases atmospheric, Hadley and Walker Circulation causing higher atmospheric pressures. The apparent paradox here is that while the incidents of heavy rainfall are predicted to increase, the ravages of drought will become generally more extensive as Hadley Circulation strength increases. ■ Associate Professor Mike Lucas is employed within the University of Cape Town’s (UCT) Zoology Department. He is also an Honorary Research Associate at the National Oceanography Centre (NOC) in Southampton, UK. He conducts much of his research in the North and South Atlantic, as well as in the Southern Ocean and in the Benguela upwelling system. He is a member of the southern African SOLAS Network, which forms part of the International SOLAS Project. Dr Mathieu Rouault is an ocean atmosphere-climate change researcher in UCT’s Oceanography Department and is also affiliated to the Nansen-Tutu Centre for Marine Environmental Research at UCT.
For learners in grades 7 - 11
Debating science. Finding solutions.
Provincial rounds: May and June 2011 Themes: Biotechnology and Nanotechnology National rounds: August 2011 Theme: International Year of Chemistry Finals: 27 August 2011
The combined images showing the centre of the galaxy.
Ten years of the InfraRed Survey Facility Infra-red Astronomy The visible light we can detect with the naked eye represents only a tiny part of the complete electromagnetic spectrum. At longer wavelengths, immediately ‘beyond’ the red lies the ‘infra-red’, or IR. While we cannot see the IR with our eyes, we can ‘feel’ it as heat. We are also restricted by our atmosphere as to which parts of the electromagnetic spectrum reach the ground, and large sections of the IR are completely absorbed by the atmosphere. However, there are well-defined bands between wavelengths of 1 and 15 microns where the radiation can penetrate the atmosphere. The IRSF works with those between 1 and 2.5 microns.
Ian Glass and Phil Charles from the South African Astronomical Observatory gives QUEST an update on this important astronomical facility in South Africa.
he world-leading Japanese-South African InfraRed Survey Facility (IRSF) and its SIRIUS camera have just completed ten years of service. This state-of-the-art installation has produced some truly impressive results. The IRSF features a 1.4 metre diameter mirror and is the third largest telescope in Sutherland. The facility is an international collaboration, which dates from an agreement signed in 1998 between Nagoya University in Japan and the South African Astronomical Observatory (SAAO). It is dedicated to working in the ‘infra-red’ part of the spectrum (see box) and has provided the most sensitive surveys of the sky at these wavelengths. The technical stuff The optics of the telescope were made in Russia of Astro-Sitall low expansion glass ceramic. The main mechanical components were made by the Nishimiura Company in Kyoto, a small concern that specialises in telescopes. The IRSF was the largest they had ever made at the time. It incorporates several unique features. For example, the azimuthal support uses an ultraprecision rail system and direct-drive motors that do not involve gearing. The telescope position is continuously monitored by highly Glass ceramic materials essentially have the properties of both glass and ceramics.
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precise optical encoders. The mount is of the altazimuth type, similar to a theodolite, which means that the altitude and azimuth axes can be driven at particular, precise speeds to track celestial objects. In addition, the mounting plate at the telescope’s focus (where the instruments are attached) needs to rotate mechanically to compensate for the Earth’s rotation. Because of the variable speed requirement, telescopes of this type have only become practicable in the era of cheap and reliable computers. The net result is a state-of-the-art telescope with highly precise tracking and pointing at the arcsecond level (better than one part in a million of a whole 360° circle). It was completed in record time, just two years, including the design phase. The telescope feeds a camera called SIRIUS, which can take images in three IR ‘colours’ simultaneously. These correspond to 1.25, 1.65 and 2.2 micron wavelengths, (about 2 – 4 times that of visible light, see Box) and use special detectors each with 1024 x 1024 pixels (picture elements). These were the largest chips available at the time and are much more complex than those in an ordinary digital camera. They are put together like a sandwich with the upper layer made of mercury-cadmium-telluride which is especially infrared-sensitive. The bottom layer contains an equal number of read-out circuits made
A visible light image of the galactic plane, including the Galactic Centre. Gas and dust completely obscures the centre of the Galaxy from view, but the IR telescope is able to see through this. Image: ESO/S. Guisard (www.eso.org/~sguisard)
The IRSF in use.
Image: SAAO/Takahiro Nagayama, Nagoya University
problems arise at the detector level, they are usually attended to by the Japanese ex-students and staff who originally worked on the construction. A portable clean room is erected whenever the SIRIUS camera has to be opened up because even the smallest loose speck of dust can lead to serious problems in the instrumental calibration.
Fish-eye view of the IRSF dome just before dawn, looking southwards. The star images are trailed in this time exposure because of the rotation of the Earth.The two Magellanic Clouds are seen as faint glowing patches to the left. The Milky Way stretches straight up above the dome and the Southern Cross and its two pointers can be seen in it, close to the Coal Sack, a dark dust cloud. Image: Takahiro Nagayama, Nagoya University
local infrastructure, which cost approx R1.3 million. At least 1/3 of the time is available to South African scientists, and there are many collaborative projects. The technical staff of SAAO provide a good deal of the support that is needed to keep the installation running efficiently. However, when the closed-cycle cooler needs to be replaced or
in a conventional silicon chip. The detectors are individually connected to the readout electronics through micronsized indium contacts. The whole camera is cooled to about -200 °C by a continuously operating refrigerator which works with helium. The telescope and imager (from Japan) each cost about $1 000 000. SAAO provided the building and
The research The first images with SIRIUS were obtained on 27 November 2000. The performance of the IRSF/SIRIUS combination has been the best in the world for most of the ten years that have elapsed and has only recently been exceeded by a much larger and (much) more expensive new survey telescope at the European Southern Observatory in Chile. At a conference held in Nagoya, Japan, ‘10 years of IRSF’, on 16-18 November 2010, Professor Shuji Sato of Nagoya University reported that 109 observers had used the telescope, that 5 760 person-nights were spent there and 17 PhDs (including three from UCT) have come out of its programmes. A total of 74 papers have been published in scientific journals. Users have come from many Japanese and South African institutions as well as from other countries. Several large projects have been conducted with the IRSF/ SIRIUS combination. The southern hemisphere is favoured over the north by the presence of the
Quest 7(1) 2011 43
Detail from the centre of our Galaxy.
Image: SAAO/Nagoya University
Seen from the southern skies, the Large and Small Magellanic Clouds are bright patches in the sky. These two irregular dwarf galaxies, together with our Milky Way Galaxy, belong to the so-called Local Group of galaxies. Astronomers once thought that the two Magellanic Clouds orbited the Milky Way, but recent research suggests this is not the case, and that they are in fact on their first pass by the Milky Way. The LMC, lying at a distance of 160 000 light-years, and its neighbour the SMC, some 200 000 lightyears away, are among the largest distant objects we can observe with the unaided eye. Both galaxies have notable bar features across their central discs, although the very strong tidal forces exerted by the Milky Way have distorted the galaxies considerably. The mutual gravitational pull of the three interacting galaxies has drawn out long streams of neutral hydrogen that interlink the three galaxies. Image: SAAO/Vanderbilt University
Magellanic Clouds and the centre of our own galaxy, the Milky Way. As the Magellanic Clouds, the nearest external galaxies, form a kind of astronomical Rosetta stone, it was natural that they should be the subject of the first survey. As an individual exposure with the SIRIUS camera covers only a small part of the sky it was necessary to combine hundreds of images from many nights of observations as a mosaic. Total areas
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of 55 square degrees of the Large Magellanic Cloud and 11 square degrees of the Small Cloud were gradually built up. The other very big project was a survey of the centre of the Milky Way itself. This region is hidden from us in visible light by intervening clouds of dust. However, in the infrared, the dust is partially transparent. The survey has therefore been able to reveal the distribution of stars towards the centre, which is much denser than in our neighbourhood of the Galaxy. A speciality of the IRSF teams has been repeated observations to find regular variable stars, which can be used as ‘standard candles’ to measure distances using the inverse-square law. At the conference it was reported that Cepheid variables, a particularly important group of stars that are used for measuring distances, have been discovered in the central region. Several of the South African users are interested in stars within ‘dwarf’ galaxies which are even smaller than the Magellanic Clouds. (The Milky Way is a much bigger spiral-shaped galaxy.) There are several of these not too far from us. In particular, the variable stars can give useful clues about their age, distance and overall chemical composition. The infrared is particularly useful for studying cool stars and objects surrounded by cool dust shells. These are frequently either stars in the process of formation from the condensation of dust clouds or else stars which are throwing off matter towards the ends of their lives. The IRSF has been extensively used to examine star-forming regions. Recently, a polarimetry capability has been added to the SIRIUS camera to measure magnetic fields in certain Inverse square law: any physical law stating that a specified physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity. A standard candle in astronomy is an object that belongs to a class whose members have a known power or wattage. Comparing the known luminosity (measurement of power or watts) of this object to its observed luminosity, its distance can be calculated using the inverse square law. Star luminosities can be measured in watts.
areas of the sky, such as those where there are dark thin filaments of dust that may be held together by magnetic forces. Polarised light is familiar in the visible region to users of Polaroid sunglasses and the new addition can be thought of as placing Polaroid filters in front of the camera. One of the obstacles to studying the large-scale structure of the Universe has been the presence of dust situated in the plane of our own galaxy. The part of the sky behind the Milky Way, known as the ‘Zone of Avoidance’ (because there are no galaxies visible) is hidden from us, making it impossible to see how we fit into the bigger picture. By using the IRSF to see through the dust, a muchimproved picture of this part of space is now emerging. A group of ‘ULIRGS’ or UltraLuminous Infrared Galaxies is also being studied. We are not yet sure how these objects will evolve, possibly into quasars or elliptically shaped galaxies. As with many ultra-luminous objects, much of the power is supplied by black holes and the infrared provides more realistic information about their total power output than visible light (which can be absorbed by internal gas and dust clouds). Into the future In the future, there is a plan to equip the IRSF with a survey spectrometer to look at the wavelength distribution of the light coming from objects in more detail than can be provided at just three ‘colours’ by SIRIUS. A new instrument called ‘TRISPEC’ is nearing completion and will include the visible region as well as the infrared. There is still much to be learned with the IRSF and its associated camera and other measuring instruments. Even though it is no longer the largest infrared survey telescope, it offers important opportunities for specialised programmes that require multiple observations to look for variability properties, as well as versatility in the addition of new auxiliary instruments. It appears likely that it will continue to be highly productive in the years to come. ■ Ian Glass holds a PhD in physics from MIT and has been connected with SAAO since 1971. He specialises in infrared astronomy and has written over 200 papers. He was responsible for the South African side in the negotiations over the establishment of the IRSF. Phil Charles is SAAO Director.
Elephants making waves.
Image: Jaco Smit
We see scientific concepts around us every day. Jan Smit explains how elephants can make waves.
Elephants and waves T he aerial photos show two elephants bathing in a shallow lake in Botswana. What is special and very rare about this photo is the wave pattern in the water. How is it created? What branch of physics are these elephants demonstrating? The elephants move their bodies up and down. This causes surface waves on the water. Notice that both do it! The waves propagate on the surface at a certain speed. The speed of such waves in a certain medium, in this case water, is constant (although it depends on the depth of the water, as will be discussed later). The wavelength, however, depends on the frequency of the wave. The higher the frequency, the shorter the wavelength. The following formula applies: wave speed = wavelength x frequency The reader may test this formula in a bath or a basin (addition of a colouring substance to the water makes the observation of the surface waves easier), or even a swimming pool. Touch the water surface with a finger tip. Then move it regularly up and down. You should see circular waves spreading out from the finger tip. The finger tip is at the centre of the waves. If you move the finger up and down faster (higher frequency), the wavelength becomes shorter. Your finger tip can be regarded as a point source, which causes the waves. Allow the water surface to calm down and repeat the experiment, but use two fingers this time, one from each hand. Insert the finger tips about ten centimetres apart. First move the fingers at the same rate up and down. Let them go up and down in phase. That means that they go up and down simultaneously. Both fingers now create waves that spread out. Where the waves meet they interfere. If two wave crests are at the same point simultaneously, a big crest is formed. If a crest and a valley meet at a certain point, the surface appears to be undisturbed. You may repeat the experiment by moving the two fingers out of phase: that is, move one up and the other one down. The same interference pattern is observed. Now back to the elephants in the lake. If you study the wave patterns you clearly see that the waves interfere. If you blank out the elephants on the photos, you can easily conclude that the waves were caused by point sources. The two elephants acted as point sources! A study of the photo leads to other interesting conclusions. If you look at the yellow water plants drifting on the surface, you see that the plants are more concentrated at the right side. That means that the water is shallower there, because water plants usually grow in relatively shallow water. At that side the waves are more clearly visible than at the other side, that is left of the elephants, where the water is deeper. Why is this so? This can be explained in the same way a tsunami is explained: The speed of a tsunami depends on the depth of the water. In
deep sea (a couple of kilometres deep), where tsunamis originate, their speeds are very high (hundreds of kilometres per hour) and the waves are nearly invisible. Wave crests are seldom higher than a meter. As the tsunami approaches land, the water becomes shallower. The speed of the wave then decreases, but the height of the wave increases, because it is a fact that the speed of a wave is high in deep water and low in shallow water. The same happens in the lake on our picture. To the right, in the shallow water, the speed is a little less than in the deeper water to the left. Hence, in the shallow water the wave crests are higher and thus better visible. ■ Professor Jan Smit is the Manager of the Science Centre, Northwest University.
15th Annual Green Chemistry & Engineering Conference in partnership with the
5th International Conference on Green and Sustainable Chemistry Washington, D.C. | June 21-23, 2011 | www.gcande.org
Quest 7(1) 2011 45
A career in chemistry? SASOL has a commitment to promoting chemistry as a career for talented young South Africans.
R A catalytic cracker at a SASOL plant.
A view across a chemical plant. Under construction.
Even chemical plants have their beauty.
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egarded as one of the most competitive bursaries on offer in South Africa, the SASOL bursary offers students, as potential bursary holders, the opportunity to focus entirely on their studies without having to be concerned over funding. SASOL is committed to nurturing talented individuals who have ambitions to become part of a new generation of experts in science, engineering and business. The longrunning bursary scheme has seen thousands of students enter the working world, many of whom now have well-established and successful careers, within the company. Khaya Hlatshwayo, an economics honours student, has had SASOL’s full support since his first year: ‘I thought SASOL would just pay for fees but they’ve been great.’ Lerato Matsio, an honours chemical engineering student, fell in love with petrochemicals in high school and chose SASOL as a South African leader in this field: ‘I love the petrochemical side of science together with the environmental side and I found a company at home that specialises on both sides.’ SASOL bursar orientation takes place in January, where new bursary-holders spend a week in SASOLburg and Secunda learning about the company’s operations and experiencing a working plant environment. All accommodation, transport and entertainment costs are covered by SASOL. Raeesah Hassim, a third-year mechanical engineering student, says that she got involved almost immediately: ‘Right at the beginning, before we even started the year, we had an orientation so that we could actually see SASOL, see the plants and how they work.’ The bursary’s benefits are extensive, to ensure that students are well equipped and prepared to embark on their academic career and to help them achieve their maximum potential. The bursary covers full tuition, residence and meals, as well as an allowance to purchase a computer, which remains with the bursar on the successful completion of the course. SASOL bursars also receive a monthly allowance and a financial incentive for academic performance.
Raeesah says that she gets recognition from SASOL for her distinctions, both through the company’s support and encouragement, but also through the incentive scheme. ‘If we get As, we get a merit award. They have campus visits every year, they track your results and say well done, they encourage us,’ says Raeesah. The SASOL Bursary Office team meets with students annually, while encouraging constant communication between them. Business managers also go out of their way to support the bursars. ‘My supervisor at the plant is amazing and keeps in contact and sees how I’m doing,’ say Lerato. SASOL believes the well-being of bursary-holders is critical to their success. To ensure students gain a well-rounded study experience, bursars get to experience how their field of study functions through ‘discipline workshops’, held by managers from the various SASOL group of companies. They also have the opportunity to be placed for SASOL vacation work, on a salary, at one of SASOL’s business units. In addition to the bursary programme, SASOL, along with the DST-NRF Centre of Excellence in Catalysis, known as c*change, the University of Cape Town and PetroSA have launched a chemistry resource pack for teachers and learners as part of the Grade 10 to 12 Physical Science curriculum. ‘We have some of the brightest minds in science working at SASOL and they continuously seek ways to develop, innovate and improve their methods that produce our range of products. We’re delighted to be able to bring that expertise to learners and educators across the country in a way that captivates them,’ says Pam Mudhray, Group community affairs manager at SASOL. Geared towards demystifying science and stimulating learner interest in the subject, the material was designed to be interactive and bring science alive in the classroom. Through extensive trials and development, the resource packs were developed in a way that demonstrates to learners the ‘real world’ application of chemistry and brings science alive. ■
WHY STUDY CHEMISTRY AT WITS? The School of Chemistry, acknowledged to be one of the top chemistry schools in Africa, has an enviable reputation for excellence in both teaching and research. The Schoolâ€™s research has consistently been rated in the worldâ€™s top 1% in the ISI Web of Knowledge. A Wits chemistry degree opens many doors. Our graduates are found all over the world both in commerce and industry in South Africa and internationally, at leading universities in this country and abroad; as well as in some of the top chemical and pharmaceutical companies both in South Africa and overseas.
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A degree in chemistry can also open doors in areas other than the chemical industry.
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Books Q A magical city Astronomy of Timbuktu. By Thebe Medupe and the Timbuktu Science Project. (Cape Town. Cambridge University Press. 2010.) Timbuktu is a place that has always held a certain fascination for me. As a child I used to look it up in the atlases on my parent’s shelves, and search for references to the city in encyclopedias and other reference works. I imagined it to be a magical city – a place of great mystery, rising from the desert like a mirage. I may have found something about the great library in Timbuktu in my searches – I can’t remember. But, whether or not I did, there is definitely a reason to be fascinated by Timbuktu. The ancient city is located in the north of Mali in West Africa and was founded by the Tuareg people about 900 years ago. The city was closely linked to three major empires of West Africa in the last 1 500 years – the Ghana Empire, the Mali Empire and the Songhoi Empire. Timbuktu was once a centre of Islamic learning and the manuscripts in the great library date from 1241, covering subjects such as astronomy, mathematics, medicine, optics, law and many others. In this book – one of Cambridge University Press’s Indigenous Knowledge Library – Thebe Medupe – himself an astronomer – explores the theories and discoveries explained by African Muslim scholars in the ancient manuscripts of Timbuktu. He starts with the history of the city, looking at its role in the three empires mentioned above, using estimates of the area of these empires as a way of explaining simple geometry and maps in geography. There is also a brief introduction to the peoples of West Africa. Once the authors launch into astronomy it is not simply an account of what these ancient Muslim scholars discovered, but an exploration of the topic in general – including some of the European astronomy of the time, showing the parallel investigation of the subject on two different continents. The book is easy to read and laid out with colourful illustrations, photographs and diagrams. There are plenty of explanations of astronomy and mathematical terms, as well as activities that help to develop further understanding of the subject. Astronomy, geometry and trigonometry are covered in a simple, accessible way that will be appealing to physical science teachers and to general readers who may not have much of a mathematical or science background. This is an excellent book to use in the classroom, school library or just to have on your shelves for reference. What the dead can tell us Steeped in Blood. The Life and Times of a Forensic Scientist. By David Klatzow (as told to Sylvia Walker). (Cape Town. Zebra Press. 2010.) Forensic science is probably one branch of science that few people don’t find fascinating! There is a plethora of television programmes on the subject – of varying degrees of accuracy and credibility – and many novels are based on the life and works of forensic pathologists. This book, however, is even more interesting for being written by a current, practising forensic pathologist, David Klatzow. David Klatzow has more than 20 years of experience in the field of forensics and has handled more than 3 000 cases – so
48 Quest 7(1) 2011
one book is not going to do his life and work justice. But, that said, his account of his early life and his path to his current career lays the foundations for the cases that he chooses to focus on. Not all of the book is about murder cases – he gives a much broader view than this – showing that there is a lot more to forensic science than dead bodies. But it is the high profile cases, such as the Brett Kebble murder, that are likely to hold the reader’s interest most – particularly because these have all been covered by our local newspapers across the country. Klatzow’s accounts of these cases give you a ‘behind the scenes’ look that holds your attention to the last word – an excellent read. Creepy-crawlies! My first book of Southern African Creepy-Crawlies. By Charmaine Uys. (Cape Town. Random House Struik. 2010.) This is another book in the ‘My first book of …’ series, produced by Random House Struik and SASOL. It is as good as all the other books in the series. Essentially, it is an introduction to invertebrates and there is an introduction that provides quite a lot of scientific detail about the group without being complicated or difficult to understand. As always, it is in English, Afrikaans, Zulu and Xhosa. The illustrations are simple and clear, with line drawings to show when the species is active, what it eats and a size comparison. The book is aimed at younger children, but will probably still be useful for those in the intermediate phase, particularly because this is one of the few books of its type that is in other African languages. All the colours of the rainbow Newman’s Birds by Colour: Southern Africa’s common birds arranged by colour. 3rd Edition. By Kenneth Newman in association with Irene Bredenkamp and Phoebus Perdikis (updated by Vanessa Newman). (Cape Town. Random House Struik. 2011.) Arranging birds by colour makes sense – that is what you tend to see first before you start looking at shape, flight patterns and all the other things that go to make up a bird’s ‘jizz’. Random House Struik have a reputation for publishing wonderful birding books – I have a huge collection even though I have not been a serious birder for years. They are just so lovely to have on your shelves. This book is no exception. The book starts with quite a detailed series of sections on birds – what they are, how they are classified, their anatomy and an explanation of the term ‘passerine’. The introduction leads into colour with details about birds legs and feet, their beaks and bills and finally their feathers. Colour in feathers is covered in some detail, as is flight and bird migration, methods of feeding, display, nests, where, when and how to look for birds and that abstract concept beloved of all birders – ‘jizz’.
Q Books There is a brief introduction to the different types of binoculars for those who are new to this passtime. The main section ‘Describing birds by colour’ is split by coloured markers on the page edge and each section starts with a list of the birds you will find in the chapter. The illustrations are clear and each species description is accompanied by a distribution map. The book is probably small enough to carry in a backpack on a day’s hike and should make identifying birds simple and easy. Succulent plants Succulent Flora of Southern Africa. By Doreen Court (revised edition). (Cape Town. Random House Struik. 2010.) Southern Africa has the most diverse and remarkable succulent flora in the world. According to the author the reason for this has never been satisfactorily explained, nor have reasons for the lack of a similar flora in other continents within the same latitudes (Australia and South America). Each major group is introduced with a review of its classification and structure. The genera within the group are described and the different species are then shown in numerous colour plates, which help with identification. There is a comprehensive glossary and an index of specific names. This is a technical book, which will appeal to the serious botanist, but also to any serious indigenous gardener. Another lovely book to have on your shelves. The wonderful ‘little’ Karoo Plants of the Klein Karoo. By Jan Vlok and Anne Lise SchutteVlock. (Hatfield. Umdaus Press. 2010.) The Karoo is one of South Africa’s signature areas and the ‘little’ or klein Karoo is particularly beloved to me. The area is encircled by the Cape Mountains and their springs and streams provide water to the lowland areas. The name Klein Karoo means ‘small area of thirst’ and the lowlands of the Klein Karoo are regarded as semi-desert. However, the mountainous uplands are very different and have a different flora as a result. The Klein Karoo has a remarkable 3 200 plant species, of which more than 400 occur only in this tiny area. The book starts with an introduction to the different habitats found in this relatively small area and the authors have divided the area into 19 major habitat types, which are then sorted into larger vegetation type units that are further subdivided into two units, water drainage areas and dry land areas. These habitat types are discussed in some detail, including freshwater and brackwater systems. There is also a good description of subtropical thicket habitat types, succulent Karoo
habitat types, transitional shrublands, and fynbos habitat types. There is a key to the plant families that are illustrated in the guide before the identification sections start, along with a glossary and illustrations of plant structure. This makes the book particularly useful for teaching. The plant species are divided into monocotyledons and dicotyledons – another useful teaching aid. Each of the 1 450 species described is illustrated with clear photographs. Game disease A Guide to Animal Diseases in South Africa: Game. By Pamela and Peter Oberem. (Pretoria. Briza Press. 2011.) Why do we need this type of book? Game farming is becoming an increasingly popular form of land use in South Africa and although there are usually vets in country areas, it is useful to have books that present animal diseases in a way that is understandable to the lay person. The book starts with an overview of game ranch animals and their classification. This is followed by a review of the main biomes in which game farms will be situated, along with a section in which the different types of grazing is explained. Management is important and is covered in some detail with explanations of the regulations covering moving game stock and problem animal management. There is a good account of general conditions such as lameness, skin conditions and digestive problems, before the dreaded infectious disease are tackled. Parasites have a section of their own as they are very common, as do plant and chemical poisoning.
Responsible Care, the Chemical Industry’s
Health, Safety and Environmental Initiative
The Chemical and Allied Industries’ Association (CAIA) through Responsible Care promotes sustainable development, protecting the environment and the health and safety of employees and the public. The safe use and management of chemicals throughout their lifecycle is ensured by promoting best practice in production, use, storage, transportation, handling and disposal.
Quest 7(1) 2011 49 www.caia.co.za
Diary of events Q Shows and exhibitions Iziko Planetarium, Cape Town Especially for children Davy Dragonâ€™s Guide to the Night Sky Come and join Davy Dragon while he learns all about the sky above so that he can fulfil his dream of becoming the worldâ€™s best flying dragon! This is a playful introduction to astronomy especially for the under 10s. Just right for inquiring young minds. From 16 April â€˘ Saturday - 12:00 â€˘ Sunday - 12:00 â€˘ 22, 25, 27 April â€“ 12:00. Especially for children aged 5 â€“ 10
Davy Dragon goes to the Moon Davy Dragon finds a strange bug that seems to be lost. He thinks it is a moon-bug and decides to take the bug back to the Moon. But is the Moon the bugâ€™s home? Join us and find out! 25 June â€“ 17 July â€˘ Monday to Friday: 11:00, 12:00 & 15:00 â€˘ Saturday â€“ 12:00 & 15:30 Sunday â€“ 12:00 and 15:30 Especially for children aged 5 â€“ 12
Make your own Davy Dragon Moon Board Game! Dates: 5 July, 7 July, 12 July, 14 July â€˘ Time: 10:00 12:00 (we start by watching the planetarium show â€˜Davy Dragon goes to the Moonâ€™) â€˘ Age: 6 - 8 years â€˘ Cost: R20,00 per workshop Tickets available at the Iziko S A Museumâ€™s Main Entrance from 1 June (open daily 10:00-17:00).
Please note - numbers are limited, so to avoid disappointment donâ€™t delay.
Celestial Clouds: A celebration of astro-photography
For teenagers and adults
Images of our Milky Way and neighbouring galaxies reveal astonishing beauty. Aside from the multitude of stars, glowing clouds of gas are seen entangled with labyrinths of dark dust lanes. The clouds are the reservoir of material, from which new stars are formed, and to which old stars expel enriched material. They are fundamental to the existence of stars - and to our own well-being in the universe. 23 July â€“ 4 December â€˘ Monday to Friday â€“ 14:00 (excluding 1 and 9 Aug, 5 Sep. 7, 28-30 Nov, 1 and 2 Dec) â€˘ Tuesday evening - 20:00 (and sky talk) (excluding 29 Nov) â€˘ Saturday - 14:30 â€˘ Sunday 14:30 â€˘ 9 August â€“ 14:30 Planetarium entrance fees: Adults 19 years and older: R25,00 â€˘ Children, students and SA Pensioners: R10,00 â€˘ Booked school groups: R6,00 per learner The Planetarium reserves the right to change or cancel advertised shows without prior notice. Closed for maintenance. The Iziko Planetarium is closed for maintenance on the first Monday of the month, excluding school holidays.
Astronomy of the Great Pyramid The pyramids of ancient Egypt were literally â€˜stargatesâ€™ - from where the spirits of dead pharaohs were believed to ascend to the stars. The largest of all pyramids - the Great Pyramid of Khufu - contains an elaborate system of shafts. At the time the pyramid was built, these were directed towards the most important stars in the sky. The planetarium, since it can be set back to ancient times, is the ideal device for demonstrating these alignments - and for exploring speculations. Until 22 July â€˘ Monday to Friday â€“ 14:00 (excluding 22, 25 and 27 April) â€˘ Tuesday evening - 20:00 (and sky talk) â€˘ Saturday - 14:30 Sunday - 14:30 â€˘ 22, 25 and 27 April â€“ 14:30
15 Billion BC Join us and look back more than 15 billion years in time, to the very edge of the observable universe! Learn about the structure and components of the universe and how to recognise the star patterns we see with the naked eye. 27 June â€“ 15 July â€˘ Monday to Friday - 13:00
Talks, outings and courses The Cape Bird Club Junior Programme All juniors, members or not, who are interested in birds are welcome on the first Sunday of
CHANGE THE WORLD â€“ ONE REACTION AT A TIME The School of Chemistry, the largest chemistry department in South Africa, is located across two centres: Westville (Durban) and Pietermaritzburg. Both centres offer both postgraduate and undergraduate studies. Apart from Chemistry majors, we are also offering focussed programs in Applied Chemistry (Westville) and Chemical Technology (Pietermaritzburg). The School is equipped with an extensive range of modern instrumentation and has a large number of postgraduate students. Research is undertaken in DYDULHW\RIÂżHOGVDPRQJVWRWKHUVQDQRWHFKQRORJ\FDWDO\VLVPHGLFLQDOFKHPLVWU\QDWXUDOSURGXFWVDQGHQYLURQPHQWDOFKHPLVWU\ The centre at Pietermaritzburg celebrated its centenary in 2010. Visit us at: http://chemistry.ukzn.ac.za
For more information on the programmes available at UKZN sms â€˜SCI9â€™ with your e-mail address to 34745, (SMS errors billed, no free SMSs, SA only, R2/sms) Mrs. J Whyte l Tel: (033 260 5184 l Email: firstname.lastname@example.org (PMB) l Mrs P Moodley l Tel 031 260 3302 l Email: email@example.com (WST)
Q Diary of events each month. Binoculars are essential equipment. Transport is not provided so grandparents and parents are encouraged to come along with their children. All school children are welcome, whether they are members or not, but the programme is not really intended for preschool children. All outings last for 1.5 hours unless stated. Booking is essential at least 24 hours ahead. Contact Heather Howell, the co-ordinator, for all bookings 021 788 1574.
Outings in May 2011 Saturday 7 May 2011 • Rondevlei – leader Merle Chalton on 021 696 8951. Tuesday 10 May 2011 • Intaka Island, Centuary City (Blouvlei) – leader Intaka Guides. Coordinator Frank Hallett on 021 685 7465. Sunday 15 May • Birding in the Swartland – Durbanville, Wellington, Malmesbury areas – leader Brian van der Walt on 021 919 2192. Coordinator Frank Hallett on 021 685 7465.
Witwatersrand Bird Club Sunday 1 May • Grootvaly wetland reserve The Grootvaly Wetland Reserve is the northern section of the Blesbokspruit RAMSAR Site. The reserve site covers 350 hectares and consists of open water, reedbeds and marshy areas which are sometimes flooded. Water birds and waders are the main attraction depending on water levels and the reserve is a good area for duck species including White-faced, Fulvous and Yellow-billed as well as Hottentot Teal and Cape Shoveler Route: From OR Tambo International Airport take the R21 south then the N12 Witbank freeway towards Springs. Take
exit 457 marked Springs/Etwatwa, turn right at the intersection and proceed south towards Springs for 6-7 kilometres. The entrance to the reserve is sign posted Grootvaly/Blesbokspruit at the gate on the left side of the road. The site is approximately 40 minutes from OR Tambo International Airport. • Meet: 08:00 • Leader: Stan Madden (082 471 6050) • SABAP2 Pentad 2610_2525 Wednesday 4 May • Cumberland bird sanctuary This is a fenced Johannesburg City Parks venue, adjacent to the Bryanston Country Club. Facilities include a hide which overlooks a small wetland. Black Sparrowhawk and African Harrier-hawk have both bred here and are often seen within the confines of the reserve. Route: Proceed north along William Nicol and turn left onto Peter Place. Cross over Main (at the Sandton Clinic) into Homestead Avenue. The entrance to the reserve is on the left opposite Bryanston Golf Course, approximately 3km from the Clinic. Parking is available on the grass verge, adjacent to the entrance. • Meet: 09:00 • Leader: Mike Fullerton (082 653 3219) Sunday 22 May • Rust De Winter nature reserve The nature reserve surrounds the dam and habitats include broad-leaved woodland, mixed woodland as well as marshy areas and open water which results in a great diversity of bird life. Specials include: Water Thick-knee and Barred Wrenwarbler. • Route: Take R21-North towards Pretoria. Shortly before reaching Pretoria turn onto the N1North towards Polokwane. Approximately 80 km north of Pretoria, turn off at the Rust de Winter / Pienaarsrivier off-ramp. Turn right and continue for
± 21 km towards Rust de Winter town. Turn right at the Rust de Winter Dam sign onto a dirt road and drive for 4 km to the entrance of the reserve on the right. *Book attendance on either firstname.lastname@example.org or (011) 782-7267 • Cost: Entrance fees payable at gate. • Meet: 07:30. • Leader: Lesley Cornish (082 806 6415) Saturday 28 – Sunday 29 May • SASOL Birds and Birding Fair – Johannesburg zoo The fair is being organised by BirdLife South Africa. Further details will be released closer to the time. Watch press for details.
Kirstenbosch Botanic Gardens, Cape Town Wednesday 4 May Natie Ferriera from Pink Geranium Nursery in Franschoek will talk on landscaped gardens in the Boland, 10:30 – 11:30. Sanlam Hall (Gate 2), contact Cathy Abbott Tel: 021 465-6440 Email: email@example.com Wednesday 18 May Morne Faulhamer, nurseryman and radio personality, will be talking on fragrant plants in your garden. • 10:30 – 11:30. Sanlam Hall (Gate 2), contact Cathy Abbott Tel: 021 465-6440 Email: firstname.lastname@example.org Wednesday 1 June Anthony Hitchcock, research horticulturist at Kirstenbosch, will be talking on cave exploration and discovery in the Western Cape .• 10:30 – 11:30. Sanlam Hall (Gate 2), contact Cathy Abbott Tel: 021 4656440 Email: email@example.com Wednesday 15 June Award winning designer David Davidson will be talking on the 2011 Chelsea Flower Show. • 10:30 – 11:30. Sanlam Hall (Gate 2), contact Cathy Abbott Tel: 021 4656440 Email: firstname.lastname@example.org
UNIVERSITY OF THE WESTERN CAPE However you see your future, if you’ve got ambition, ability and drive UWC is the place to be! UWC is home to 7 faculties: • • • •
Economic and Management Sciences Dentistry Natural Sciences Law
• Community and Health Sciences • Arts • Education
Postgraduate research opportunities include but are not limited to: Pharmacology, Pharma ceutical Chemistry, Biotechnology, Bio-Informatics, Advanced Materials Chemistry, Nanotechnology, Ground Water Resource Development, Integrated Water Resource Management, Public Health,Museum and Heritage Studies, International Trade Law, Transnational Criminal Law, Orthodontics, Periodontics, Restorative Dentistry and Science & Mathematics Education. Online applications are available at www.uwc.ac.za by Mid-May 2011 UNDERGRADUATE QUERIES For more information call us on 021 959 3900/1/2, visit us at www.uwc.ac.za or connect with us on the ‘The UWC Future Students Facebook Group’ or UWCstudents2b on twitter POSTGRADUATE QUERIES For more information call us on 021 959 2451/3920, visit us at www.uwc.ac.za or connect with us on the Division for postgraduate studies via facebook at ‘DFPS UWC’
LORNE UWC AD 2010.indd 1
3/29/10 9:53:32 AM
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From Euclid to Soccer City how maths is used in stadium design
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How green are our stadia? Sustainability and the FIFA 2010 Soccer World Cup ™
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52 Quest 7(1) 2011
Q Back page science Stranglers of the tropics and beyond Tropical forests contain more than half of Earth’s terrestrial species, and contribute more than a third of global terrestrial carbon and a third of terrestrial net primary productivity, says ecologist Stefan Schnitzer of the University of WisconsinMilwaukee. The trouble is, rampant woody vines, or lianas, are choking trees, changing tropical and temperate forest ecosystems. Tropical forests are indeed experiencing largescale structural changes, the most obvious of which may be the increase in lianas, according to Robert Sanford, an NSF programme director. Lianas are found in most tropical lowland forests. However, intense competition from lianas (‘non-self-supporting structural parasites that use the architecture of trees to ascend to the forest canopy’) for above- and below-ground resources, limits tropical tree growth and survival. The invasion of the lianas For example, in a tropical moist forest on Barro Colorado Island, Panama, researchers found that the proportion of liana infestation in the crowns of trees changed from 32% in 1967-68 to 47% in 1979, to nearly 75% in 2007. Lianas have also overgrown other tropical forests, but a tree need not live in the tropics to fall victim to lianas; more than 80 non-native liana species have invaded North America. For people who escape to tropical climes each winter, a strangler-free paradise may be in the woods they left behind. Source: National Science Foundation
Oriental bittersweet vine is obscuring trees in forests far beyond the tropics. Image: US Fish and Wildlife Service
Resources, choices hinder women in science, researchers find Unequal access to resources and gender-linked lifestyle choices may be to blame for the current under-representation of women in science in the US and in other countries, researchers say.
advantage. Teams adjust their cars to minimise drag, but then it’s up to the drivers to find ‘the draught’ and to trust the drivers behind them to literally ‘bump’ them into Victory Lane. Just don’t do this on the road.
Women in science.
Stephen Ceci and Wendy Williams of Cornell University in Ithaca, NY reviewed 20 years of previously generated data on gender discrimination and the state of women in science. They concluded that programmes to fight discrimination in the workplace seem to have succeeded, and that other factors probably explain today’s paucity of women in math-intensive fields. Discrimination is rare Although discrimination in the science field does occur, the pair suggested, incidents are rare, relatively minor and work as often in favour of women as against them. Men and women of comparable resources publish similar quantities and quality of work, gain near-equal grant funding, and earn similar promotions and salaries, the researchers also found. However, they said, fewer women than men pursue careers in science because women are more likely to make personal choices, both freely and under pressure, that hamper their advancement. These include deferring a career to raise children, following a spouse, or caring for parents. Reporting their findings in an online issue of the research journal Proceedings of the National Academy of Sciences, Ceci and Williams warned that continued focus on discrimination might be costly and misplaced. Efforts should instead be aimed towards education and policy changes to better address the underlying factors that discourage women from becoming scientists, they argued. Courtesy of PNAS and World Science staff.
Using the drag.
Image: Wikimedia Commons
Imagining Mars This composite of three artists’ renderings from 1975 was only wish fulfilment for an unnamed JPL artist; however, the landscape and the rendered shapes took into account what was known about Mars that year. Compared to Earth, Mars is further away from the light of the sun, very cold and very arid, and has a thin atmosphere rich in carbon dioxide but little nitrogen, an environment distinctly inhospitable to complex, Earth-like, carbon-based life forms. ‘Life on Mars’ was envisioned as low to the ground, symmetrical and simple. The artist drew silicon-based life forms, probably coached by others, perhaps scientists, who had thought about such possibilities. Peculiar saucer-like shapes stood only slightly above ground level, root-like structures reached outward for growth resources; a bundle of cones faced many directions for heat, light or food. Instead of reality, the images embodied the artist’s hope and anticipation of what future Martian exploration would find. Source: NASA
Drag and draughting If you have you ever ridden your bicycle behind a lorry or bus you will have noticed how it is so much easier to keep up, but when you drop behind you have to pedal hard against air resistance to go as fast. Well, engine power is constrained at superspeedways in the United States like Daytona and Talladega, so teams use aerodynamics to gain an
The 1975 renderings.
MIND-BOGGLING MATHS PUZZLE FOR Q uest READERS Q uest Maths Puzzle no. 16 Place the words ONE, TWO, THREE, FOUR, FIVE, SIX, SEVEN and EIGHT into a 5x5 grid of letters. The words must be in a straight line, but can be in any direction, including diagonally.
Answer to Maths Puzzle no. 15: The solution is 20 cents. Since the deposit is R1.60 LESS than the cost of the soda, the total for the cost of the soda must be R1.80. Now add this to the deposit of 20 cents and this equals the R2 you paid for the soda including the deposit.
Win a prize! Send us your answer (fax, e-mail or snail-mail) together with your name and contact details by 15:00 on Friday, 10 June 2011. The first correct entry that we open will be the lucky winner. We’ll send you a cool Truly Scientific calculator! Mark your answer ‘Quest Maths Puzzle no. 16’ and send it to: Quest Maths Puzzle, Living Maths, P.O. Box 478, Green Point 8051. Fax: 0866 710 953. E-mail: email@example.com. For more on Living Maths, phone (083) 308 3883 and visit www.livingmaths.com.
Quest 7(1) 2011 53